This, the second General Information Yearbook, is designed to assist the reader in understanding Assessment findings. Report 03/04-GIY relates especially to the learning areas assessed during the third and fourth years of the project: social studies, music, mathematics, and science. It presents an overview of National Assessment, describing its purpose, history, and methodology, and then goes on to devote a chapter to each of the major steps in the intricate research/dissemination process. The chapters are organized to tell how the assessment is carried out and subsequently how its data are reported and used. National Assessment's (NAEP) principal objective is to assess the changes over time in educational achievement of four age groups in the U.S. In addition to the national results for each age group, results are reported within each age level for certain major subpopulations, such as geographic region and sex. To do so, NAEP had developed two baseline measures: (1) an estimate of the percentage of persons in each of the populations who gave a certain response to a specific exercise, and (2) an estimate of the difference between the performance of a subpopulation and the performance of the total age population. Measures of change will reflect comparisons of these statistics over time. (Author/JM) Primary type of information provided by report: Procedures (Overview).