This article presents lessons learned from the Men as Partners (MAP) Program in South Africa. MAP is an ongoing, multi-faceted intervention designed to engage men in reducing gender-based violence and to promote men’s constructive role in sexual and reproductive health, including HIV/AIDS. The program is carried out through a partnership of civil society organizations collaborating with governmental and academic institutions to transform the behaviors of men and the norms of masculinity. This article is based on (a) qualitative interviews with professionals from MAP Network organizations and a summary of a small-scale evaluation carried out with MAP participants; and (b) on reflections by the authors, who are directly involved in the ongoing implementation and management of MAP in South Africa. The article provides a case study of a complex intervention seeking to change men’s attitudes and behaviors through the use of an ecologic approach that utilizes strategies at many levels to effect personal and social change. As such, it has important implications for work with men in South Africa and elsewhere.