The data for this report describe the tested achievement and educational status of a cohort based on a nationally representative probability sample of 15,362 10th-graders in 752 public, Catholic, and other private schools, who were studied in the spring term of the 2001-02 school year. The base-year data collection for the Education Longitudinal Study of 2002 (ELS:2002) is the first wave of a new longitudinal study of high school students that continues a series of nationally representative longitudinal studies conducted by the United States Department of Education's National Center for Education Statistics (NCES) over recent decades. Future survey waves will follow both students and high school dropouts and will monitor the transition of the cohort to postsecondary education, the labor force, and family formation. Although the base-year study comprised surveys of parents, teachers, school administrators, and library media specialists, as well as the cohort of high school sophomores, to remain concise, this report draws primarily on data from students, the primary unit of analysis for the study. This document is organized in the following sections: (1) Introduction; (2) Sociodemographic and Educational Profile of American High School Sophomores in 2002; (3) School Experiences; (4) Extracurricular and Sports Activities; (5) Sophomores' Time Use; (6) Tested Achievement- the Reading and Mathematics Proficiency of High School Sophomore Class of 2002; and (7) Values, Expectations, and Plans. The following are appended: (1) Technical Notes and Glossary; and (2) Standard Error Tables. (Contains 40 tables & 35 figures.)