Objective: Dual use of male condoms and female contraceptives is widely advocated for unplanned pregnancy prevention, yet college students often neglect condoms. This feasibility and acceptability study assessed the efficacy of a self-guided home-based condom-promotion intervention among college students in heterosexual relationships. Participants: Fifty-nine couples who had been together at least 30 days and had penile-vaginal sex at least twice weekly. Methods: Assessments were done at baseline and 6 months later. Outcomes were frequency of condom-unprotected penile-vaginal sex and four psychosocial mediators of condom use. Results: Frequency of unprotected penile-vaginal sex decreased over time. Several corresponding psychosocial mediators showed change, particularly among women. Using actor-partner interdependence modeling, men's increase in condom use was associated with an increase in women's sexual pleasure. Conclusion: Findings support implementation of a brief, self-guided, home-based condom-use intervention that could lower incidence of unplanned pregnancy and STIs among heterosexually active college students.