Women's colleges and universities persist around the world, even as the vast majority of tertiary institutions are open to men and women. In nearly every nation, women can attend even the most elite formerly all-male universities, and in several nations women are the majority of all college students. Questions therefore arise about the continued need for a single-sex sector in the 21st century. In this study I examined the contribution of these institutions to their national systems of education and society. I used a qualitative, comparative, multiple case study approach to understand 14 diverse women's colleges and universities in nine nations on five continents. Five key roles emerged: access, campus climate, gender empowerment, leadership development, and cultural paradox. I make recommendations for research and practice.