This report profiles the American high school sophomore in the 1989-90 school year using data from the National Education Longitudinal Study. It describes the tested achievement of sophomores in mathematics and patterns of course-taking in mathematics, as well as English, science, and social studies. The report summarizes sophomore reports of how they and their families make decisions about school, work, and college plans. Also examined are sophomores' reports of their future plans, including educational expectations. Just over 11% were not able to perform simple arithmetic operations on whole numbers, but about one-fourth had mastered simple problem solving, but not complex problem solving. Just over 22% had achieved the highest level of mathematics mastery, that is, conceptual understanding and complex problem solving. Geometry and foreign language were among the key "gatekeeper" courses for college admission. Overall, gender differences were small, but students did differ in mathematics achievement by socioeconomic status and by high school program placement. While black and white students had similar educational expectations, blacks were much less likely to have taken geometry and foreign languages. Student characteristics are displayed in 29 tables and 12 figures. Five appendixes present supplemental information. (Contains 69 references.) (SLD)