The gains in knowledge and changes of attitudes of students in undergraduate sexuality courses in two different academic disciplines were compared to those of their peers without college sexuality education in a variety of other psychology courses. All students had similar scores on tests of sexual anatomy, behavior, and health at the start of the semester, but the students enrolled in sexuality courses exhibited much larger increases in knowledge regarding these topics when their courses were done. Sexuality education clearly matters, but there is room for improvement; despite gains in knowledge, the sexuality students' scores were less than perfect. Students in both the sexuality courses and other psychology courses maintained neutral attitudes toward same-sex sexual orientation and gender reassignment surgery, and these attitudes did not change following enrollment in a semester-long course in sexuality education. (Contains 2 tables and 1 footnote.)