Although Mexican Americans have one of the oldest histories of the peoples of the United States, Chicano/a history as a recognized field within United States history is new, with the first historiographic essays in Chicano history appearing in 1970. Acceptance by historians has been gradual, but as of the 1990s both the American Historical Association and the Organization of American Historians have formally recognized the field of Chicano history. Despite formal acceptance, many historians still view the field as questionable, primarily regional, and limited to the Southwest. This essay examines the origins of the field and three decades of scholarship by Chicano/a historians. Chicano history emerged as a new field affected by various philosophical and ideological perspectives, including the new social history; European and Latin American progressive and radical traditions; and Whig and liberal American historical traditions. Major issues in Chicano history include (1) the periodization and degree of historical continuity between pre-twentieth-century Mexicans and twentieth-century Mexican Americans; (2) the stagnation or decline perspective of nineteenth-century Mexican society in the Southwest; (3) the origins of Mexican labor organizations and the influence on them of the American labor movement; (4) the role of women in the reproduction of Chicano/a identity and culture, and the lives and struggles of Mexican women as central in Chicano/a history; (5) the imagining of and changes in identities—i.e., national, ethnic, regional, local, gender; and (6) organization, politics, and political ideology.