Using data from the National Longitudinal Study of Adolescent Health, this study examines the impact of high school cohort composition on the educational and labor market outcomes of individuals during their early 20s and again during their late 20s and early 30s. The authors find that having more high school classmates with a college educated mother has positive effects on college attendance in the years immediately following high school, but no statistically discernible effects on college attendance and college completion as individuals reach their late 20s and early 30s. Some evidence suggests that the delay in college attendance associated with the composition of one's high school cohort may affect household income during the late 20s and early 30s.