We examined how college students' knowledge of evolution is associated with their self-described religious beliefs and the evolution-related content of their high school biology courses. On average, students entering college know little about evolution. Religious beliefs, the absence of evolution-related instruction in high school, and the presence of creationism-related instruction in high school were all associated with significantly lower scores on an evolution exam. We present an ordered logistic model that helps to explain (1) students' diverse views and knowledge of evolution, and (2) why college-level instruction about evolution often fails to significantly affect students' views about evolution.