Within capstone design courses, the relationship between faculty and students can be classified as mentoring, where instructors fulfill functions that support career and psychosocial development of the students. Unlike traditional mentoring relationships, however, matching student teams to faculty mentors is not simply a process of one mentor and one mentee choosing each other. Project, team, and course structures are all dominant factors, resulting in both cross-sex and same-sex mentoring relationships. Literature on mentoring relationships in higher education has produced conflicting reports on which match yields better outcomes. Thus understanding the implications of same-sex and cross-sex relationships can be helpful in enabling faculty to effectively support the development of all students. This study applies an empirically derived model of capstone mentoring to data from a 2011 national survey of students enrolled in capstone design courses. The survey addresses students' perceptions of faculty teaching and their self-reported learning gains, and the data analysis presented in this paper focuses on similarities and differences based on the sex-pairing. The results provide preliminary insights regarding the impact of sex differences on the capstone mentoring relationship, and thus contribute to a more complete understanding of design teaching.