College mismatch occurs when a student enrolls in a college with a selectivity level that is above (overmatch) or below (undermatch) his or her academic qualifications. A primary concern regarding college mismatch is that it could lead to social stratification. However, studies on mismatch provide mixed results and fail to articulate the determinants of college mismatch and the effects of college mismatch on degree attainment. My dissertation comprises two studies. The first study examines the role of social capital in college mismatch. Using data from ELS:2002, I find students from families with a lower level of social capital are more likely to apply to and enroll in an undermatched college, and less likely to apply to and enroll in an overmatched college. I further find intergenerational alignment of educational goal is associated with both college undermatch and overmatch. Results suggest that enhancing family social capital may help low-SES students to engage in broader college searches and find a college with a better academic fit. The second study examines the association between college mismatch and degree attainment within a timely manner. I find students who enrolled in a matched college are less likely to graduate within 6 years than those who enrolled in an overmatched college, but have a higher probability of obtaining a bachelor’s degree than those who enrolled in an undermatched college. Furthermore, I find there is no significant difference in obtaining a bachelor’s degree between matched and mismatched students as far as institutional characteristics are concerned. Results suggest that scholars need to be cautious before claiming systemic mismatch penalty or match advantage.