This study examines the effect of beginning at a community college on baccalaureate success in science, technology, engineering, and mathematics (STEM) fields. In addition, drawing upon a new concept of "STEM momentum," this research explores whether and how STEM baccalaureate success is related to early STEM momentum, as well as whether and how such momentum is shaped differently in community colleges as compared with public 4-year institutions. Results indicate that, overall, students beginning at community colleges were less likely to achieve STEM baccalaureate success. However, this negative effect was reduced to some extent by the positive influence of community colleges on a key STEM momentum indicator, quality points students achieved in STEM courses during the first term, which in turn positively impacted STEM baccalaureate success.