This publication offers a demographic and socioeconomic profile of Puerto Ricans in the mainland United States as of 1990. A section on population analyzes size, growth, and geographic distribution. A section on demographic characteristics covers age composition, sex composition, and household structure and marital status. A section on socioeconomic characteristics presents data on education, labor force participation and employment, occupations, and income. This section indicates that the educational attainment levels of Puerto Ricans in the United States are somewhat below those of many other groups, although Puerto Ricans have made significant strides since 1980. In 1990 for the first time more than half (56 percent) of Puerto Ricans had completed 4 years of high school or more. However, poverty remains a serious and persistent problem among Puerto Ricans, with the proportion of Puerto Rican families below the poverty level essentially double the proportion of Cuban and other Hispanic families and five time the proportion of White families below the poverty level. Data are from the 1990 United States census data. Ten tables, 16 figures, and 6 supplemental figures are provided. (Contains 11 references.) (JB)