Among the protest movements of the 1960s, the Mexican American Youth Organization (MAYO) emerged as one of the principal Chicano organizations seeking social change. This in-depth study of MAYO is based on interviews, letters, diaries, position papers, participant observations, and secondary sources such as newspapers and articles. The introduction presents an overview of theories on social movements and a paradigm of exogenous (external) and endogenous (internal) etiology of the Chicano movement. Exogenous factors included the Civil Rights, New Left, Antiwar, and Black Power movements, as well as the War on Poverty. Chapter 1 analyzes the historical endogenous antagonisms that played a significant role in fostering the climate for change necessary to produce the Chicano Movement, the Chicano Youth Movement (CYM), and MAYO. Chapter 2 analyzes the historical antecedents of the CYM (1920-30), the emergence of the Mexican American Movement in the late 1930s to its demise in 1952, changing conditions following World War II, and the early 1960s. Chapter 3 introduces MAYO as an organization: its creation, purposes, goals, ideology, protest strategies and tactics, structure, leadership, gender factor, and use of its own newspapers. Chapter 4 examines MAYO's educational reform agenda and presents case studies of 3 of the 39 school boycotts in which MAYO was involved. In chapter 5, MAYO's early social change activities, conference participation, and struggle to acquire resources are examined. Chapter 6 reviews MAYO's political empowerment agenda. Chapter 7 analyzes how MAYO's success in forming the Raza Unida Party led to its demise. An epilogue highlights MAYO's orientation and explains its contributions to Texas and Chicano political history. Four appendixes include "El Plan Espiritual de Aztlan," MAYO membership requirements, the Crystal City School Walkout demands, and "El Plan de Del Rio." Contains references in notes and an index. (SAS)