In this study, a theoretical model is tested to examine factors shaping the decision to pursue STEM fields of study among students entering community colleges and four-year institutions, based on a nationally representative sample of high school graduates from 2004. Applying the social cognitive career theory and multi-group structural equation modeling analysis, this research highlights a number of findings that may point to specific points of intervention along students' educational pathway into STEM. This study also reveals important heterogeneity in the effects of high school and postsecondary variables based on where students start their postsecondary education: community colleges or four-year institutions. For example, while high school exposure to math and science courses appears to be a strong influence on four-year beginners' STEM interest, its impact on community college beginners' STEM interest, albeit being positive, is much smaller. In addition, college academic integration and financial aid receipt exhibit differential effects on STEM entrance, accruing more to four-year college students and less to those starting at community colleges.