This dissertation is a comparative study of personalistic movement-parties. Movement-parties are a particular type of parties that organizationally and ideologically straddle the line between political parties and social movements. While existing works have earlier identified movement-parties of the Green and Post-Industrial Extreme Right types, this dissertation identifies a third type of this party family, the Personalistic Movement-Party. Unlike other members of this party genus, personalistic movement-parties have in the Latin American context proven highly durable, and have remained in semi-institutionalized states for prolonged periods, despite attempts at party change.

The failure of this party type to institutionalize is posited to be a product of a complementary logic: (1) The dominance of a leader who has contempt for the constraints of more traditional parties, and (2) a fundamentally different conception of the role of the political party and party institutionalization by a significant sector of the party elite, where a great divide exists on even the desirability and value of becoming a more traditional political organization.

After identifying this construct and its significance, a range of theoretical propositions on party change are examined in the empirical chapters of the dissertation. Through the method of elite interviewing with 40 members of the PJ/FpV in Argentina, and 80 members of the PRD in Mexico, the characteristics and logics of the personalistic movement-party are examined in depth. The study arrives at the conclusion that personalistic movement-parties are not unitary actors, but remain in a profound and permanent tension between party builders and movement advocates with sharply diverging readings of the perceived political reality, and following diverging logics.