Students' first-year academic success plays a critical role on their overall development in college, which implies the need to concentrate on identifying ways to improve students' first-year academic success. Different from most research on the subject, this study attempted to combine the sociological perspective of college impact with a psychological perspective to synthetically explore the causal relationship of specific types of self-concept and college involvement with academic success of medical students. A longitudinal study was conducted using 519 matriculates at a medical university in mainland China. We conducted the Cooperative Institutional Research Program freshmen survey and the Your First College Year survey to collect data of the pre-college and college academic and social self-concept, college involvement components, and some input characteristics. The academic success was measured by the first-year grade point average. A pathway analysis was conducted and showed the following results. Having high academic self-concept, being engaged in class and putting effort in homework or study directly contributes to increasing college achievement. Students' pre-college achievement and self-concept, faculty interaction, and homework involvement positively affected students' college academic self-concept development, which indirectly improved average grade point. These findings contribute to our understanding of a student's ability to interact with his or her collegiate environment and to experience academic success.