This article tests hypotheses about the electoral support of Canada's first—and perhaps most significant—third party. It demonstrates that two micro-economic concepts, price elasticity of demand and efficiency of production, describe accurately the material base of Progressive party support. It thereby subsumes the study of agrarian parties and voting behaviour within a more general (public choice) framework. It also clarifies and substantiates important elements of the conventional wisdom about Progressive support, and it suggests means which might also shed new light upon the Co-operative Commonwealth Federation and Social Credit.