In this study, we examined patterns of persisting in and switching from an intended college major (chosen in high school) in the third year of college. We focused on science, technology, engineering, and math (STEM) major persistence because of the national effort to increase those entering STEM careers. Results showed differences in persistence by academic field as well as by gender, parental income, and first-generation college student status with the largest variation by ethnicity. Further examination of STEM major persistence showed that high school performance in math and science, taking advanced placement exams in STEM, articulating positive science self-efficacy beliefs, and professing a goal of obtaining a doctorate were also related to persistence in varied ways across STEM majors. (Contains 3 footnotes, 9 tables, and 1 figure.)