Changes in the demographic-socioeconomic characteristics of Mexican Americans, Puerto Ricans, Cubans, Central and South Americans, and Hispanos were examined using primarily 1970 census data. The study briefly reviewed the history of these groups--when they first came to the U.S., the types of immigrants, etc.; noted their geographic distribution within the U.S. and the possible implications of such geographic patterns; and examined the levels of education and school attendance, fertility, and such socioeconomic characteristics as out-marriage, use of English language at home, absence of a Spanish surname, occupation, income, marital status, family size, and employment. The groups were compared to determine their similarities and differences. Among the findings were: about 60% of the U.S. born of Mexican and Puerto Rican origin and about 70% of the Hispanos were high school graduates; while only about 9% of the native men of Mexican descent aged 55 and over had finished high school, 56% of their male descendants aged 20 to 24 had at least this much schooling; among those who completed high school only the Mexican and Hispano women had fertility rates above those of the non-Spanish women, Cubans and Central and South Americans had rates significantly lower. This report contains a description of some of the study's theoretical aspects, some of the broader findings which pertain to all the groups, the findings for each of the five groups, and tabular data. (NQ)