Students whose high school biology course included evolution but not creationism knew more about evolution when they entered college than did students whose courses included evolution plus creationism or whose courses included neither evolution nor creationism. Similarly, students who believed that their high school biology classes were the primary source of their views of evolution knew more about evolution than did students who claimed that religion was the primary source of their views about evolution. Students who described their religious views as conservative or middle-of-the-road knew less about evolution than did nonreligious students or those who described their religious views as liberal/progressive. To our knowledge, this is the first measure of how students' experiences in high school biology courses affect their knowledge of evolution when they enter college.