This paper uses three decades of studies with Rhesus monkeys to investigate the intergenerational effects of early life advantage. Monkeys and their offspring were both randomly assigned to be reared together or apart from their mothers. We document significant intergenerational effects of maternal presence. We also estimate, for the first time, the intergenerational complementarity of early life advantage, where the intergenerational effects of maternal rearing are only present for offspring that were mother-reared. This finding suggests that parenting is the primary mechanism driving the intergenerational effects. Our paper demonstrates how studies of primates can inform human development.