Is there an optimal school starting age? Updated

It depends: older children perform better on standardized tests, but evidence of older school starting ages on long-term outcomes is mixed

University of Toronto, Canada, and IZA, Germany

University of Toronto, Canada

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Elevator pitch

There is a widely held belief that older students, by virtue of being more mature and readier to learn at school entry, may have better academic, employment, and earnings outcomes compared to their younger counterparts. There are understated, albeit important, costs to starting school later, however. Compulsory school-attendance laws may allow these same older pupils to drop out of high school earlier, which could adversely impact their employment; entering the workforce later also has implications for lifetime earnings and remittances to governments. Overall, research suggests that school-age entry policies can improve student achievement in the short term, but the long-term impacts are currently not well-understood.

Children’s primary school entry ages vary
                        worldwide, 2020

Key findings


While most countries have been lowering school starting ages, an opposite trend has been occurring in the US.

Being the oldest student within a group has large positive effects on short-term outcomes such as test scores, special-needs diagnosis, and leadership.

Test score age gaps are of a similar magnitude across social/economic status, race/ethnicity, gender, deciles of birth weight, gestational age, and school quality.

Grade retention policies and the postponement of tracking may offset some of the disadvantages associated with younger school starting ages—especially among students with low-income backgrounds.


The optimal school-entry age is unknown and likely to depend on contextual factors, such as access to high-quality early childhood education, compulsory schooling laws, grade retention policies, and tracking systems.

More parents in the US are delaying their children’s school entry, despite mixed evidence of its benefits.

Findings on the effects of being older within a student group are inconclusive with respect to longer-term outcomes like educational attainment, employment, and earnings.

Author's main message

In many countries, the positive impact of older school-entry ages on standardized test scores and other school-related outcomes has been well-established. However, due to inconclusive evidence, it is currently unknown whether and how these benefits persist in the long term. As such, policymakers need to carefully consider their unique institutional context when determining students’ optimal school starting age and the best way to implement it. Four especially important institutional considerations include: the prevalence of high-quality early childhood education, early grade retention policies, tracking systems, and compulsory school-attendance laws.

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