This report provides guidance and documentation for users of the combined base-year to third follow-up data of the Education Longitudinal Study of 2002 (ELS:2002). ELS:2002 is sponsored by the National Center for Education Statistics (NCES) of the Institute of Education Sciences, U.S. Department of Education. The base-year and follow-up studies were conducted through a contract to RTI International. This manual contains information about the purposes of ELS:2002, the base-year to third follow-up data collection instruments, the sample design, and data collection and processing procedures. The manual provides guidance for understanding and using data from all components of the base year and its three follow-ups. Appended are: (A) Glossary of Terms; (B) Cross-Cohort Comparisons; (C) Facsimile of the Third Follow-Up Survey Instrument; (D) FS Flow Charts; (E) Occupational Crosswalk: O*NET and ELS:2002 Classifications; (F) Weight Adjustments; (G) Design Effects; (H) Unit Nonresponse; (I) Item Nonresponse; (J) Responsive Design Bias Estimates; (K) Extant Sources; (L) Extant Variable List; (M) All Variables; and (N) F3 Composites.