The National Education Longitudinal Studies (NELS) program is a long-term effort that now encompasses the educational experience of youth from three decades, the 1970s, 1980s, and 1990s. The NELS program studies the educational, vocational, and personal development of students at various grade levels, and the personal, familial, social, institutional, and cultural factors that may affect that development. The NELS program currently consists of three major studies: (1) the National Longitudinal Study of the High School Class of 1972 (NLS-72); (2) High School and Beyond (HS&B); and (3) the National Education Longitudinal Study of 1988 (NELS:88). This monograph discusses opportunities for drawing comparisons across the cohorts that comprise the three studies, as well as some of the differences in survey content and design that may limit the possibilities of drawing valid comparisons. The focus is on dropouts in 1982 and 1992. A major difference is that the HS&B database contains information only for late dropouts (persons dropping out after the spring term of sophomore year) while the NELS:88 began with an eighth grade cohort. Implications of this design difference are discussed. Issues of the comparability of tenth grade samples and differences in defining dropouts in the two samples are reviewed. Three appendixes (which comprises three-fourths of the document) discuss the second followup dropout questionnaire item overlap and present the 1982 HS&B and 1992 NELS:88 dropout questionnaires. (Contains 23 references.) (SLD)