This article describes a survey study of college students' epistemologies about biology and learning biology. Specifically, it examines the differences between science and nonscience majors and their changes in epistemologies over the course of a semester of instruction. This study utilized the Colorado Learning Attitudes about Science Survey for Biology (CLASS-Bio) with 171 participants from both science and nonscience major biology courses. Preinstruction results showed that students in the science major course had a significantly higher percentage of favorable responses (responses aligning with experts' views) than students in the nonscience major course. Postinstruction results reversed the pattern, with the nonmajors outperforming the majors. Through matched comparisons, we found that the science majors shifted toward more "novice-like views" over the course of the semester, whereas the nonscience majors by and large exhibited positive gains in their epistemologies. This unanticipated result for nonscience majors is addressed at some length in the Conclusion section.