This document summarizes National Center for Education Statistics (NCES) data on the topic of lifelong learning, which is defined broadly as "all types of learning activities in which adults engage" and which includes both "traditional" and "nontraditional" (returning) postsecondary students. All 11 NCES data sets that report on the educational efforts of adults and ways they might be used to examine the topic of lifelong learning are briefly described. Information on the NCES databases is organized into four categories: longitudinal data on secondary school students; cross-sectional data on postsecondary students; longitudinal data on postsecondary school students; and cross-sectional data on adults. The following data sets are discussed: National Longitudinal Study of 1972; High School and Beyond: Sophomore Class of 1980 and Senior Class of 1982; National Educational Longitudinal Study of 1988; Integrated Postsecondary Education Data System; National Postsecondary Student Aid Study; Beginning Postsecondary Students Survey; Baccalaureate and Beyond; National Adult Literacy Survey; International Adult Literacy Survey; National Household Education Survey: Adult Education, 1991 and 1995; and Recent College Graduates Survey. Seven tables are included. Appended are a partial list of relevant NCES reports on topics related to lifelong learning and a listing of NCES working papers to date. (MN)