Background Growing up in poverty undermines healthy development, producing disparities in the cognitive and social‐emotional skills that support early learning and mental health. Preschool and home‐visiting interventions for low‐income children have the potential to build early cognitive and social‐emotional skills, reducing the disparities in school readiness that perpetuate the cycle of poverty. However, longitudinal research suggests that the gains low‐income children make during preschool interventions often fade at school entry and disappear by early elementary school. Methods In an effort to improve the benefits for low‐income children, the REDI program enriched Head Start preschool classrooms (study one) and home visits (study two) with evidence‐based programming, documenting positive intervention effects in two randomized trials. In this study, REDI participants were followed longitudinally, to evaluate the sustained impact of the classroom and home‐visiting enrichments 3 years later, when children were in second grade. The combined sample included 556 children (55% European American, 25% African American, 19% Latino; 49% male): 288 children received the classroom intervention, 105 children received the classroom intervention plus the home‐visiting intervention, and 173 children received usual practice Head Start. Results The classroom intervention led to sustained benefits in social‐emotional skills, improving second grade classroom participation, student–teacher relationships, social competence, and peer relations. The coordinated home‐visiting intervention produced additional benefits in child mental health (perceived social competence and peer relations) and cognitive skills (reading skills, academic performance). Significant effects ranged from 25% to 48% of a standard deviation, representing important effects of small to moderate magnitude relative to usual practice Head Start. Conclusions Preschool classroom and home‐visiting programs for low‐income children can be improved with the use of evidence‐based programming, reducing disparities and promoting complementary benefits that sustain in elementary school.