When discussing educational inequality, one message comes up time and again: if you really want to make a difference, you need to invest in the earliest years of life. That idea has been popularised in part by the work of economist James Heckman, who showed that investments in young children often generate particularly high social returns. However, this has sometimes been taken further than Heckman himself would argue today, leading some to believe that later investments make little difference. A new longitudinal study in Educational Researcher suggests that reality is more nuanced.

Eric Dearing and colleagues followed 226 children from low-income families for an impressive 26 years. Rather than simply examining how many educational opportunities these children experienced, they also asked when those opportunities occurred. They distinguished between early childhood, the primary school years, and adolescence. The study is based on a remarkably rich longitudinal dataset.

The researchers examined several types of educational opportunities, including:

• an enriching home environment;
• high-quality childcare or schooling;
• participation in organised after-school activities;
• living in a socioeconomically advantaged neighbourhood;
• upward economic mobility within the family.

They then investigated how these opportunities related to two outcomes measured at age 26:

• educational attainment;
• annual earnings.

Educational opportunities mattered throughout childhood. Opportunities in early childhood increased the likelihood that children would continue their education beyond high school. Somewhat surprisingly, opportunities during the primary school years were especially important for completing a four-year university degree. Opportunities during adolescence also increased the likelihood of pursuing further education.

The earnings pattern at age 26 was slightly different. Opportunities during primary school and adolescence predicted higher income, whereas opportunities in early childhood were not statistically significant predictors. The authors point out, however, that the financial returns to education often become more pronounced later in adulthood, particularly during people’s thirties and forties.

Perhaps the most striking finding was not about any single developmental stage, but about the accumulation of opportunities over time. Children who continued to experience educational opportunities throughout childhood consistently achieved better outcomes than those who experienced very few.

The authors’ models illustrate this clearly. Fewer than half of the children who experienced no educational opportunities were expected to continue their education beyond high school. In contrast, among children who experienced at least one educational opportunity during each developmental stage, around 85% were expected to continue into further education, and more than one-third eventually completed a four-year university degree.

Of course, the study also has important limitations. It is observational, meaning it identifies associations rather than causal effects. In addition, it focuses on a relatively small sample drawn from a well-known but non-representative American longitudinal study. The authors themselves therefore stress the need for replication in larger samples.

This study does not challenge the importance of investing early. On the contrary, early childhood clearly matters. What it does challenge is the popular idea that only the earliest years matter. Educational opportunities during primary school and adolescence also appear to contribute to later outcomes, even after accounting for earlier opportunities.

That is an important nuance for education policy. Investing in young children remains a wise strategy. But if we stop there, we leave opportunities untapped. Or, put differently: the lesson is not early or later, but early and sustained.