A mail survey of university graduates from a predominantly White university suggests how limited undergraduate demographic diversity could be leveraged to increase its impact. University graduates who recalled more undergraduate courses in which faculty discussed ethnic and cultural diversity reported more multicultural competence and volunteer service 5 years later. The number of multicultural classes recalled by graduates predicted these outcomes most strongly for graduates who reported fewer close college friends from different ethnicities, religions, or sexual orientations. Given the ethnic homogeneity of many undergraduate students' friendship networks, the discussion focuses on how other types of cross-group friendships and exposure to multicultural curriculum could promote multicultural awareness and commitment. (Contains 2 tables and 3 figures.)