Educational experiences of a cohort of 1,247 mathematically talented youths (initially identified in 7th/8th grade by the Study of Mathematically Precocious Youth) were analyzed after high school and after college to identify factors correlated with high and low academic achievement in math and science in college by students with extremely high ability. Almost all students had achieved highly by conventional standards (e.g., 85% had received bachelor's degrees). Using a quantitative definition of academic achievement in college, we found that 22% were high academic achievers and 8% were low academic achievers in math and science. Variables predictive of high academic achievement (in order of strength) were precollege curricula or experiences in math and sciences, family characteristics and educational support variables, attitudes toward math and science, and differences in aptitude.