The present study used the daily diary method to investigate the role of achievement in adolescents' patterns of time use in the academic and social domains. A diverse sample of over 700 ninth grade students completed three-page checklists every night for 14 consecutive nights, providing information on their time use for the day. As hypothesized, averaged over the 14-day study period, high achieving adolescents spent more time studying without spending less time with their friends than lower achieving students. However, differences between high and low achieving students were not just in their average time use, but also varied on a daily basis. These daily differences helped explain how high achieving students were able to spend more time overall than lower achieving students across these two domains. The role of achievement in adolescents' time use patterns was similar for boys and girls and across ethnic groups.