The following paper estimates the impact of initially declaring and then departing from a STEM major on college dropout and degree completion rates for students in the Beginning Postsecondary Students Longitudinal Study. The results show that students who initially declared a STEM major and switched to a "non-STEM" area of study were less likely to complete a bachelor's degree and more likely to dropout of college than those who stayed in their initially declared major. These outcomes were most severe for students who switched early in their academic trajectory and among those whose parents do not have a bachelor's degree.