Southern politics changed dramatically since the enactment of the 1965 Voting Rights Act. Most notably, we witnessed the emergence of a competitive two-party system and greater electoral participation by blacks. During this period we also saw a substantial liberalization in the voting behavior of southern Democratic members of Congress. A number of researchers have tried to use constituency variables to explain variability in liberal voting by southern legislators. The purpose of this paper is to develop and test a constituency explanation of liberal voting by southern Democrats based on the ideological leanings of white voters, the size of the black constituency, urbanization and the strength of the Republican congressional candidate. The effects of constituency variables on two measures of liberal voting (ADA scores and party unity scores) are analyzed for each odd-numbered year between 1981 and 1987. The findings of this study suggest that constituency variables do impact on southern Democrat's liberalism with the willingness of southern whites to support liberal candidates exerting the strongest effect. The presence of a larger proportion of black residents is not consistently related to the measures of roll-call liberalism analyzed. Finally, the paper demonstrates that southern Democratic support for liberal positions increased independent of constituency characteristics.