This study estimates the relative and unique effects on changes in cri
tical thinking of three dimensions of students' college experience: cu
rricular exposure, formal classroom and instructional experiences, and
out-of-class experiences. Students' classroom/instructional and out-o
f-class experiences both make positive, statistically significant, and
unique contributions to gains in critical thinking above and beyond s
tudents' precollege characteristics and level of critical thinking. Th
eoreticians have long speculated that students' academic and nonacadem
ic experiences jointly influence change, and this study supports that
belief. The design and instruments in this study may be of interest to
persons involved in assessment or the study of college impact.