After reviewing the research design, objectives, and basic conceptual model for the National Longitudinal Study of the High School Class of 1972 (NLS), this document describes the survey plan and issues for the third followup survey. Data analyses--both those that are in progress or planned--are summarized. These activities include composite score analysis, weight computation, tabular summaries, methodological studies, descriptive analyses, and issue-oriented analyses. Previously unattempted analyses, within a causal modeling framework, are proposed. Information on time schedules, consultation outside the sponsoring agency, and respondent reporting burden is also provided. The appendices include: (1) a detailed description of the field test study, its findings, and recommendations for the full-scale third followup survey; (2) alternate forms of the proposed questionnaire for the third followup; (3) results of the principal components analyses; and (4) a list of users of the NLS data. (CP)