This report presents a taxonomy of precisely what is studied, where, and by whom, in universities, community colleges, and postsecondary trade schools in the United States. It is based on data from the National Longitudinal Study of the High School Class of 1972 (NLS-72) and the High School and Beyond/Sophomores (HSB/So) survey of high school sophomores scheduled to graduate in 1982. With the addition of the HSB/So transcript sample covering the period 1981-1993, it is brought up to date. Section 1 describes how the data bases on which the taxonomy of courses and analyses of course-taking, credits, grades, and degrees were constructed and edited. Section 2 presents the long-term educational attainment of 2 cohorts: the NLS-72 and HSB/So students. Section 3 presents the taxonomy of over 1,000 course categories in postsecondary education that was derived from the HSB/So transcript sample. Section 4 uses 809 course categories to demonstrate how enrollments were distributed over instructional type. Section 5 focuses on the core courses taken by the two cohorts of students. Section 6 presents data on what students studied and how this has changed since the 1970s. Section 7 presents data on grade inflation and course failure rates. A conclusion provides next steps and illustrative issues. Two appendixes provide information on statistical procedures and data sources. (Contains 38 references.) (MDM)