Friendships that cross social boundaries foster the development of important civic and prosocial attitudes among college students. The present study complements and extends prior quantitative findings with qualitative description, in college students' own voices, of the learning and growth that take place within boundary-crossing friendships, including those crossing boundaries of religious, secular, and spiritual (RSS) identity; political beliefs or partisanship; race or ethnicity; and other social differences. We explored how the processes that take place within these relationships might facilitate this learning and growth. Our data consisted of transcripts from 55 focus groups with 268 college students at 18 U.S. institutions. Participants described four friendship outcomes: humanizing difference, developing empathy, shifting attitudes, and desiring justice. We also identified processes that facilitated these outcomes, noting patterns we observed across participants. Our findings provide evidence of student learning and growing through educationally powerful peer relationships. When college students graduate with these capacities, they seek solidarity and justice rather than fomenting hate and social division, advancing the civic mission of higher education.