This study examines whether high school relationship and marriage education can affect students' relationship skills and if effects vary between sites having mandated and self-selected course participation. Based on an original data set (n = 222), results show that course exposure can result in a significant, positive change in students' relationship skills, although only at certain schools and for certain students. Mandated treatment appears to garner better results, those from two-parent families show the most consistent gains in relationship skills across schools, and severely economically disadvantaged school samples appear not to show gains. The importance of these results for practitioners and policy makers is discussed. (Contains 6 tables and 14 notes.)