Research Questions.

The Perry Preschool Project, the longest-running experimental study of an early childhood education program (targeted rather than universal), demonstrates how such interventions can yield long-term personal, societal, and intergenerational benefits for disadvantaged populations. The evidence is clear: investments in high-quality early childhood education and parental engagement can deliver returns even 50 years later. The program’s findings remain scientifically robust, particularly when analyzed through rigorous small-sample inference methods. The program’s findings also contradict common criticisms of preschool, as, when measured correctly, treatment effects on IQ do not fadeout. This paper draws insights from both the original founders and recent empirical studies, emphasizing the critical role of parental involvement in early education. The authors advocate for a scientific agenda focused on understanding the mechanisms behind treatment effects, rather than replicating specific programs. The analysis also underscores the broader implications of early childhood interventions for social mobility and human capital formation. Analysts of early childhood education should recognize that although credentials and formal curricula contribute to successful programs, the true measure of quality lies in adult-child interactions, which play an essential role.

2024: Baulos, Alison. et al: Perry School Project at 50: What lessons should be drawn and which criticisms ignored?

All of the UK’s major political parties have recently declared their intentions to significantly expand state subsidies for childcare outside the home, including for babies from the age of nine months. It’s frequently said that universal “early childhood education” is a way to “give every child the best start in life”. It’s believed this will improve children’s educational outcomes, reducing social inequality; and also that it will empower women and boost the economy by enabling more mothers to go to work.

But what is the evidence for these claims? In this latest report, Maria Lyons takes an in-depth look at the academic literature from both the UK and abroad, and finds a worrying lack of support for many of the supposed benefits of universal childcare.

2024: Lyons, Maria: Universal Childcare: Is it good for children? Civitas.

This study examined early external childcare in relation to development from age 7 to 20. A Swiss sample was used (N = 1,225; 52% male). Development included multi-informant-reported externalising behaviour, internalising problems, prosocial behaviour, delinquency, and substance use. Growth curve models revealed that, dependent on the informant, time in a daycare centre was related to increased externalising and internalising problems until at least age 11. It was not related to delinquency. Roughly three days per week at a daycare mother or playgroup was related to increased externalising behaviour. External family care was associated with increased prosocial behaviour. Finally, time in a daycare centre was associated with fewer externalising but more internalising problems and substance use for children from vulnerable backgrounds. This relationship with substance use lasted to age 20.

2022: Averdijk, M, et al: External childcare and socio-behavioural development in Switzerland: Long-term relations from childhood into young adulthood

In England, the best available evidence indicates that some use of high-quality ECEC is beneficial from age 3 for all children and from age 2 for disadvantaged children. There are limited data on children aged 0-2. Positive outcomes are strongly associated with the quality of ECEC and the child’s home learning environment.

2021: Early Childhood Education and Care: Policy Briefing, UK Parliament

This study attempts to analyse the long-term impact of a universal, low-cost childcare programme for 0-4 year olds introduced in Quebec in 1997, on a cohort of 2000 children. An earlier paper (2008) documented an increase in childcare uptake and maternal labour but “a large, significant, negative shock to the preschool, non-cognitive development and health of children exposed to the new programme, with little measured impact on cognitive skills”.

Subsequent research confirmed that the negative impact persisted as the programme matured. The study looks at the impact on older ages, on both cognitive and non-cognitive development, health and crime, assessing young people in their teens and early 20s. The authors found no consistent evidence on the impact of the programme on cognitive test scores. They did find however a significant decline in self-reported health and life satisfaction as well as a sharp increase in criminal behaviour relative to peers not exposed to the programme. These results appeared predominantly in boys, who also showed the greatest deterioration in non-cognitive skills.

The authors contrast these results with the more positive outcomes of targeted programmes in the United States (e.g. the Perry Project, the Abecedarian) and suggest that because universal programmes (the Quebec programme being comparable in quality to other International universal childcare provision) are generally poorer quality they do not have the same benefit for the general population. The study also suggests that near-term impact can serve as an indicator of long-term impact.

2019: M Baker et al: The Long-Run impact of a Universal Childcare Programme. American Economic Journal: Economic Policy

The SEED study (sample size 4, 5000) is a major longitudinal study designed to provide evidence on the effectiveness of early years care and education (ECEC) and the short and long-term benefits of investment in ECEC. It aims to assess children's outcomes at ages 2, 3, 4, 5 and 7. The 2020 revised report looked at how children who started ECEC from age 2 went on to perform in the first year of school, in terms of educational achievement, cognitive development and socio-emotional development. ECEC was defined as formal group (i.e. nurseries and playgroups), formal individual (i.e. childminders) and informal individual (i.e. friends, relatives and nannies).

The researchers found an association between informal ECEC (friends and relatives) and better verbal ability in Year 1 across all groups. An association was found between formal group ECEC and verbal ability, but only for children with a less enhancing home learning environment. There was relatively little evidence for the impact of ECEC and EYFSP (educational achievement) outcomes. There was limited evidence for the effects of ECEC on cognitive development. Differing from earlier SEED studies in which findings were somewhat more positive, the association between ECEC and socio-emotional development were mainly negative, particularly where there where children were spending higher numbers of hours in formal childcare settings.

In practice these results mean that “the effects associated with ECEC overall are small, making only a small difference to development, not always identifiable in practice”. Moreover, “home environment factors, such as parenting, the quality of parent-child relationships and the home learning environment had a considerable influence on educational outcomes assessed during year 1.”

2017, revised 2020: Impact Study on Early Education Use and Child Outcomes up to age five years Department of Education Study of Early Education and Development (SEED)

A rapid evidence review published by NHS Scotland in 2017 aimed to identify indicators of quality in childcare associated with different outcomes for children, as well as looking at the “effect sizes” of different ECEC programmes in Scotland. (An effect size of 0.3 would be considered weak, whereas 0.7 would be considered strong.) The review confirms what other studies have shown, that all children can potentially benefit from childcare, but the quality must be high and where quality is low, childcare can have “detrimental effects on children”. It also confirms that the greatest impact is made by targeted programmes, with universal programmes also having a “positive, albeit weaker effect with the biggest impact on disadvantaged children”.

The review also reiterates that research on children under three is “more equivocal” with differences in results possibly relating to the age of starting and quality of the nursery. As with all age groups, “childcare effects are moderated by family background with outcomes dependent on the relative balance of quality of care at home and in childcare”.

2017: Scobie G and Scott E. Rapid evidence review: Childcare quality and children’s outcomes. Edinburgh, NHS Health Scotland

The Growing Up in Ireland study had an initial infant cohort of 11,000 children, systematically and randomly selected from the Child Benefit Register, starting at the age of 9 months. The completed samples at age 3 totalled nearly 10,000 children and at age 5 just over 9,000 children. The report examines the effects of non-parental childcare (i.e. friends and family, childminder or group setting) on socio-emotional development at age 5, testing pro-social skills (e.g. sharing, kindness) as well as negative behaviours (e.g. conduct problems, hyperactivity, emotional difficulties and peer problems). “Overall the effect of childcare type at age three on socio-emotional development at age 5 is small and childcare type explained less than 1 per cent of variance in children’s scores.” Children’s health, gender, background and family characteristics (including structure and parenting style) all had a stronger impact on children’s outcomes than childcare. On the key question of whether centre-based care affects the outcomes for different groups of children (i.e., does childcare compensate for socio-economic disadvantages), reports from parents differed from those of teachers. According to parents’ assessments, there were no differences between advantaged and disadvantaged children, whereas teachers found “small but significant improvements” in pro-social behaviour and “marginally lower socio-emotional difficulties” for those in centre-based care compared to those cared for at home. Conversely, for more advantaged children centre-based care was related to increased socio-emotional difficulties. The authors concluded, “we find some limited evidence to suggest that access to centre-based care has more beneficial effects for disadvantaged children, but the effects are small and not sufficient to level the playing field”.

2016: Russell H., Kenny, O and McGinnity F., Childcare, Early Education and Socio-Emotional Outcomes at Age 5: Evidence from the Growing Up in Ireland Study: The Economic and Social Research Institute, Dublin

This Policy Brief produced in 2016 for the European Commission’s Directorate-General for Employment, Social Affairs and Inclusion (carried out by the RAND Corporation) reviewed international literature on childcare. The report makes the general statement that there is “overwhelming evidence that ECEC improves educational outcomes” and that “Children who have attended ECEC for longer show higher cognitive performance levels and educational attainment, provided quality is good” (15).

More specifically with regard to the under threes, it states “A longer duration of centre-based care up to the age of three is associated with better language and cognitive skills at school age.” To support this claim it references six studies, three of which focus on children older than three (Sylva 2010; Sammons 2002; Anders 2011), one which did not address language or cognitive skills but rather aggressive behaviour (Dearing 2015) and one which found that care received at home was a more important factor for verbal ability than childcare (Broburg 1990). Only one of the six studies cited as evidence for the claim actually included children under three and examined the impact of early centre-based care on later cognitive ability (Broburg, 1997). The was a longitudinal study of children in a Swedish town with a sample size of 146 children (53 in centre-based care, 33 in family care) enrolled at 16 months of age. 123 of these children were tested again at 8 years old, and the study concludes that “children who had spent more months in centre-based daycare before they were 40 months old obtained higher scores on tests of cognitive ability than did other children”.

The report goes on to say that “generally, children who have attended ECEC for longer show higher cognitive performance levels and educational attainment (provided that the ECEC is of good quality).” The report cites eight studies. Two of these (Buechner et al. 2007 and Caille 2001) are not in English so I was unable to review them. One of the papers (Driessen 2004), a large-scale longitudinal study of ECEC in the Netherlands (involving over 30,000 students from 600 schools) actually concludes the opposite of what is claimed, finding “no effects of daycare attendance [or] preschool attendance…on the cognitive or non-cognitive competencies of elementary school children.” Three of the studies (Sylva et al 2004, Votruba-Drzal et al 2004 and Gorey 2001) are not strictly relevant because they focus on older children and/or children who could be deemed “at risk for school failure” for various reasons. One US study (Votruba-Drzal et al. 2013) using data on approximately 6000 children did find evidence to “suggest that centre-based preschool was supportive of the math and reading skills development of sample as a whole”. It also found that “both centre- and home-based care for 2-year-olds…were beneficial for children from lower income, less educated and less enriching family contexts, helping to diminish the cognitive skills gap between more and less advantaged children.” I was unable to access the full text to determine what exactly is meant by “home-based care” in this context.

The final study (Mullis et al 2012) refers to the results of the Progress in International Reading Study (PIRLS) which showed that “across the 28 EU member states, reading skills at age ten were correlated with the number of years children had been in preschool: children who had been for three years or more performed better than children who had been for between one and three years, who in turn performed better than children who had been for less than a year”.

The authors conclude that “the evidence for a positive effect of an early starting age for children up to the age of three on ECEC outcomes is mixed, with results depending on the type of care, and the quality of care, and the family background”. Negative, neutral and positive effects depend on “the relative balance of quality of care in the home and childcare. The best outcomes occurred for those children for whom the quality of childcare was higher than the quality of care at home”.

2016: Janna Van Belle: Early Childhood Education and Care (ECEC) and its long-term effects on educational and labour market outcomes

Objective: To investigate whether the total amount of time in childcare through the first 3 years of life was associated with children's receptive vocabulary, externalising and internalising problem behaviours at age 4-5 years, and whether this association varied for different types of childcare. Conclusions: More time in centre-based childcare (but not other types of care) through the first 3 years of life was associated with higher parent-reported and teacher-reported externalising problem behaviours, and lower parent-reported internalising problem behaviours but not with children's receptive vocabulary ability at school entry.

2015: Gialams, A. et al: Time spent in different types of childcare and children's development at school entry: an Australian longitudinal study

A comprehensive international review of the childcare literature carried out in 2015 by Melhuish et al reiterates the point made above that the quality of childcare experience matters, as does the interaction between in-home and out-of-home experience. In general, for all ages, the authors concluded that “high-quality childcare has been associated with benefits for children’s development, with the strongest effects for children from disadvantaged backgrounds. There is also evidence that negative effects sometimes occur.”

For the under 3s specifically, the evidence is more equivocal, with “some negative effects, some null effects and some positive effects”. Early research was focused on whether daily interruptions to maternal care would influence the development of secure attachment. A major study carried out in the United States by the National Institute of Child Health and Human Development (NICHD 1997-2006, see more on this below) found no association between either the quantity or the quality of care and attachment security at 15 and 36 months.

Some studies have shown elevated levels of externalising behaviour (for instance, aggression, hyperactivity and conduct problems) with early age and high-intensity childcare, effects which remain into later childhood and adolescence. Other studies, however, failed to find an association. Results on the behavioural impact of long hours in childcare for the under threes are therefore mixed. For cognitive, language and educational effects, the findings are more consistent and positive. This is particularly true for children in centre-based care starting between ages 2 and 3 and particularly, though not exclusively, for children from disadvantaged homes.

The authors conclude that for the general population high-quality childcare in the first three years has benefits for cognitive, language and social development but for children of a low socio-economic status low-quality childcare can produce a “dual risk”, that is to say, possible deficits in language or cognitive development. There is some evidence that high levels of childcare, particularly group care in the first two years of life, may elevate the risk of developing anti-social behaviour. This may be related to high levels of poor quality, centre-based care in the first year of life. Significantly, while recent large-scale studies have found effects in terms of both quantity and quality of childcare, these effect sizes are “about half those for family factors”.

2015: Melhuish et al: A review of the research on the effects of Early Childhood Care and Education

939 children, 6 months to 4 years, children’s aggression based on teacher reports at 2, 3 and 4. Between the age of 2-4, the effect of age of entry on aggression faded to negligible levels. Norway has one year of maternal leave, universal generally high-quality care...Found that even high intensive centre-based care from 1-4 years had “at most, faint and fading consequences for children’s aggression”.

2015: Dearing, E. Age of entry into ECEC as a predictor of aggression: faint and fading associations for young Norwegian children: Psychological Science

Little evidence for under-three universal childcare programmes. This study looks at this gap specifically. Sample size approx. 1,500 children, in Chile. Explores associations between 2-year-old attendance at daycare and child development (cognitive and socio-emotional outcomes) at ages 3 and 4. Found – whilst controlling for child, family and maternal characteristics – positive association for cognitive development, insignificant for socio-emotional development. Moreover, more hours association positively with cognitive and negatively with socio-emotional. The association between attendance at centre-based care and socio-emotional outcomes is more negative for lower-income households relative to children from higher-income households.

2014: Narea, M. Does early centre-based care have an impact on child cognitive and socio-emotional development? Evidence from Chile: CASEpapers 183. Centre for Analysis of Social Exclusion, London, UK

The purpose of this longitudinal study was to examine, in a large representative English sample, the influence of different forms of childcare on children's behavioural and emotional development around the age of school entry.

Results: The strongest and most consistent influences on behaviour and emotional problems were derived from the home, including lower socio-demographic status, poorer maternal caregiving, parental stress/maternal mental health problems, as well as child gender (being a boy). Non-parental childcare had small effects on child outcomes. One finding that did emerge was that children who spent more time in group care, mainly nursery care, were more likely to have behavioural problems, particularly hyperactivity.

Conclusions: These findings suggest that interventions to enhance children's emotional and behavioural development might best focus on supporting families and augmenting the quality of care in the home.

2013: Stein, A et al: The influence of different forms of early childcare on children's emotional and behavioural development at school entry

Lots of evidence that high-quality centre-based EPPE is beneficial – but low-quality shows no cognitive benefits in Sylva 2008 as compared to those who do not attend preschool. Many studies comment that “the quality of the home learning environment has been found to be more important for children’s intellectual and social development than parental occupation, education or income” (95).

This study (95 children in Porto, Portugal) looks at the combined effects of home environment and ECEC, a complex interaction. Associations between the quality of family environments and ECEC programmes as they relate to language, literacy and communication outcomes. The study looked at 1-3-year-olds, followed up at 4-6. The study finds positive associations between high-quality of home environment and preschool outcomes; positive associations between high-quality ECEC and preschool outcomes: But, the detrimental effect of poor-quality ECEC on children’s outcomes, i.e. low-quality ECEC may “hinder or even nullify” the positive effects of home environment quality on children’s language and literacy skills”. (Also issue raised by Watamura, 2011).

2013: Pinto, A et al: Effects of the home environment and centre based child care quality on children’s language, communication and literacy outcomes: Early Childhood Research Quarterly

This study (sample 1364) looked at the relationship between non-relative childcare up to age 4 1/2 and functioning at age 15 years. Both quality and quantity of childcare were linked to adolescent functioning. Effect sizes were modest but similar to the effect sizes observed at younger ages. Higher quality early care was associated with higher cognitive-academic achievement at 15 and less externalising behaviour. More hours in care was associated with more risk-taking and impulsivity at age 15 (i.e. linked to earlier problem behaviours from longer hours of care).

2010: Belsky et al: Do effects of early child care extend to age 15 years? Child Development

English sample of 1016 families, the use of childcare was investigated at 3, 10, 18 and 36 months. Child behaviour problems and social competence were assessed by a maternal questionnaire. No effect of the amount or type of childcare on disruptive behaviour at 36 months, the main predictors being maternal care. “Overall there was no evidence of adverse consequences of childcare in the first three years, and some limited evidence of benefits.”

2009: Barnes, J: Experience of childcare in England and socio-emotional development at 36 months: Early Childhood Development and Care

“Parenting also matters. Typically, for cognitive outcomes, the effect sizes for preschool childcare are only about a half to a third as large as those for parenting.”

This is a large-scale (2857 children), longitudinal study but focuses on over 3s. However, important for the discussion on the relative importance of the home learning environment (HLE). The study finds that HLE is the most significant factor in literacy and numeracy achievement, over and above SES/social class (household income, parents’ education). “For five-year-old literacy achievement, the effect size for HLE was greater than that for any of the variables reflecting social class. For five-year-old numeracy, HLE again had the largest effect size, followed by SES, then household income and mother’s education. For both 7-year-old reading and mathematics, the largest effect size was still for HLE, followed by SES, mother’s education, father’s education and household income”. “While other family factors such as parent’s education and SES are also important, the extent of home learning activities exert a greater and independent influence on educational attainment”.

“The home learning environment is important for school readiness in addition to benefits associated with preschool. The home learning environment is only moderately associated with SES and parents’ educational levels, indicating that low SES homes sometimes score highly and conversely, high SES homes sometimes score poorly on HLE measures.” It refers to studies which show parenting behaviours are learnable, and changes in parenting are associated with child development (see e.g. Love et al 2005, under 3s.) See also Hannon, Nutbrown and Morgan 2005 - UK programme where parents received support to improve child literacy in the preschool period.

Advocate combination of high-quality childcare from three and promotion of strategies to involve parents - the best way to help improve achievement for disadvantaged children.

2008: Melhuish et al: Effects of the Home Learning Environment and Preschool Centre Experiences upon Literacy and Numeracy Development in Early Primary School: Journal of Social Issues

This study evaluates studies of child care with specific attention to the impact of age at entry and the amount, quality, and type of care on children's adaptive functioning.

Results: Children who began care early in life and were in care 30 or more hours a week were at increased risk for stress-related behavioural problems. Elevated risk was more likely if they had difficulties interacting with peers or had insensitive parents. Children in daycare centres had higher language scores and early school achievement, especially if they came from disadvantaged backgrounds and the centres offered high-quality care. Attending arrangements with 6 or more children increased the likelihood of communicable illnesses and ear infections, albeit those illnesses had no long-term adverse consequences.

Conclusions: Childcare is a multidimensional phenomenon. Guidance on when to place a child in non-parental care and what kind of care to use is complicated because of the multiplicity of sometimes offsetting effects on children. Childcare experiences interact with experiences at home and the child's own characteristics, and research indicates that the quality of childcare matters.

2007: Bradley, R. et al: Child care and the well-being of children

Often described as a major study (despite a relatively small sample of approximately 1300 children) this research looked at children from birth to 4 ½ years old and assessed the influence on child development of maternal-only care vs different types, quality and quantity of non-maternal care. Childcare was defined as “any care provided on a regular basis by someone other than the child’s mother”, for more than 10 hours per week.

In terms of quality, the results showed that children who experienced higher quality childcare “consistently showed a somewhat better cognitive function and language development across the first 3 years of life”. The most important feature for predicting this development was the language used by the caregiver. Higher quality childcare also predicted greater school readiness at 4 ½, as reflected in standardised tests of literacy and numeracy. Although this association was found, “the link was not a strong one. Family and parent features were more important predictors than child care quality” and “the differences between outcomes for children in higher and lower quality care were small relative to the differences associated with family characteristics”. The links between quality of care and social outcomes were also weak, with social outcomes more related to maternal sensitivity and interaction with her child.

In terms of quantity, the study concluded that “the amount of time children spend in child care from infancy through age 4 ½ is not related to their cognitive outcomes prior to school entry. Children who spend more hours in childcare, however, show somewhat more behaviour problems...than those in fewer hours of child care”.

In terms of the type of childcare, the study concluded that “centre-based care is associated with both positive and negative effects.” Although linked to better cognitive development and more positive social behaviours, large group and centre-based settings were also associated with “more problem behaviour just before and just after school entry”.

The study’s main conclusion was that “children who were cared for exclusively by their mothers did not develop differently than those who were also cared for by others”. “Parent and family characteristics were more strongly linked to child development than were child care features...family and parenting experiences were as important to the wellbeing of children who had extensive child care experiences as family and parenting experiences were for children with little childcare experience.” The study also states that “one of the most important and consistent predictors of child cognitive and social development was the quality of the mother-child interactions” and that the quality of the family environment (e.g. well-organised routines, books and stimulating play materials, enhancing experiences in and out of home) all lead to more socially and cognitively advanced children independent of their childcare experience. Although the amount of time children spend in childcare does impact mother-child relationships, whether it was positive or negative depended on the family’s culture.

2006: Study of Early Childcare and Youth Development: Findings for Children to Age 4 ½ Years: National Institute of Child Health and Human Development (NICHD)

Abstract (14,000 children data analysed)

This paper examines the effects of different child-care arrangements on children’s cognitive and social proficiencies at the start of kindergarten. Overall, centre-based care raises reading and math scores, but has a negative effect for socio-behavioural measures. However, for English-proficient Hispanic children, the academic gains are considerably higher and the socio-behavioural effects are neutral. The duration of centre-based care matters: the greatest academic benefit is found for those children who start at ages 2–3 rather than at younger or older ages; negative behavioural effects are greater the younger the start age. These patterns are found across the distributions of family income. The intensity of centre-based care also matters: more hours per day lead to greater academic benefits, but increased behavioural consequences. However, these intensity effects depend on family income and race.

2005: Loeb et al: How much is too much? The influence of preschool centres on children’s social and cognitive development. Economics of Education Review