A summary of the 1966-1979 Southern Youth Study (SYS), a 4-wave longitudinal research project intended to produce information on career development and decision-making processes and influences of rural southern youth from economically-disadvantaged counties, presents data collection procedures, an overview of instruments and variables, descriptions of the raw data file and software, suggestions for users, the codebook, and appendices containing instruments and questionnaires. Procedures used to select data sources are described. Data collection procedures for the four waves are differentiated. A listing of the variables used in at least one SYS survey is given. Tables present senior class enrollment distribution for SYS states (Alabama, Georgia, Louisiana, Mississippi, South Carolina, and Texas) and the samples (categorized by year into black and white, male and female) for the four SYS waves. The raw data file and accompanying data management software are briefly described. A sample codebook entry with explanations precedes the full codebook, which presents the original questions, response categories, labels, response codes, and frequency counts for each response code. Appendices include the instruments from the third and fourth waves, United State Census occupational and industrial classifications, and questionnaires used in the various states for the first three waves. (MH)