A broad-bases study of the ways in which Hispanics in the United States are dealing with the English language is presented. The report analyzes the latest reliable language data collected by the U.S. census, including the 1980 national census, and finds a steady shift in language usage from Spanish to English among immigrants and native-born Hispanics. Chapters address these topics: (1) theory and method in the analysis of language shift; (2) the size of the Spanish origin group; (3) the structure of the Spanish origin group; (4) a nativity profile of the Spanish origin group; (5) language shift among immigrants; (6) language shift among the native-born; (7) regional aspects of language shift; (8) the urbanization of the Spanish language population; (9) ethnic origins of this population; (10) modeling population growth in this group; and (11) projections of its size and composition. Appended materials include notes on interpreting the 1980 census data, technical data, and a comparison of the University of Quebec at Montreal and U.S. Census Bureau models. (MSE)