Urie Bronfenbrenner

A Russian-born psychologist who argued that child development couldn't be understood from lab experiments alone, and built ecological systems theory to show how family, school, community and culture all press on a child at once. That framework reshaped developmental psychology, and Bronfenbrenner put it into practice directly: he was one of the architects of Head Start, the 1965 US program that brought early education to poor children, arguing that real-world intervention was itself a form of scientific inquiry.