Can early intervention have a sustained effect on human capital?

Evidence on the sustained effect of early intervention is inconclusive, with many studies experiencing a dissolution of treatment effects once the program ends. Using a randomized trial, this paper examines the impact of Preparing for Life (PFL), a pregnancy to age five home visiting and parenting program, on outcomes in middle childhood. We find little evidence of cognitive fade-out at age nine, with significant treatment effects on cognitive skills (0.67SD) and school achievement tests (0.47-0.74SD) that are of a similar magnitude to those observed at the end of the program. There is no impact on other school outcomes and earlier effects for socio-emotional skills are no longer evident. While about 50 percent of the sample is retained at age nine, the treatment groups are still balanced on all key baseline characteristics and the results are robust to inverse probability weighting. Mediation analysis suggests that ~46 percent of the treatment effect on cognitive skills is explained by improvements in early parental investment. This study demonstrates that boosting children's early cognitive skills can reduce school-age inequalities five years after program completion, yet continued investment may be needed to break longstanding inequalities in other dimensions of skills.