The agrarian populist movement of the late nineteenth century remains among the largest social movement and third-party revolts in American history. It embodied a full-scale critique and mobilization against the inequities of the Gilded Age, and its influence stretched well into the Progressive and New Deal eras. While most accounts of the movement and party’s emergence and rapid demise have centered on economic conditions and interests, we link movement and third-party emergence and failure to the institutional arena second only to partisan politics in its impact on southern society at large, namely organized religion, particularly evangelical Protestantism. This article offers the first systematic analysis of the extent to which organized religion in the South channeled the mobilization of agrarian populism. The results both support and contradict the argument that agrarian populism was rooted in organized southern religion by suggesting that evangelical Protestantism channeled the mobilization of the Farmers’ Alliance movement but not the People’s Party. While white southern evangelical religion served as a potent cultural resource and mobilizing structure for the movement, the move to partisan politics helped create a disjuncture between movement and party from which Populism never recovered.