What explains variation in how committed postwar Democrats were to civil rights? I use evidence from state delegation behavior at national party conventions to assess this. I examine two types of issues: challenges to the credentials of all-white southern delegations and efforts to change the platform language on civil rights issues. While the latter is widely known, the former are more obscure but, I argue, important indicators of how strongly committed some state delegations were to civil rights. I use archival materials to trace the story of how these issues came onto the party committee’s agenda in the first place and then assess the correlates of state delegation voting behavior. In 1948, the strongest predictor of being willing to unseat the all-white Mississippi delegation was the increase in Black population percentage in a state. More states, however, were willing to strengthen the civil rights platform language, and here state population size was the strongest predictor. These results, though, obscure important variation, with a number of relatively smaller, whiter states in the upper Midwest playing a key role. Taken together, these findings elucidate variation in the civil rights preferences of non-southern Democrats, shed new light on debates about the civil rights realignment, and demonstrate the potential of using state delegation voting behavior as evidence.