The National Longitudinal Study of the High School Class of 1972 (NLS) is a large-scale longitudinal survey effort. The current data tapes contain base-year (1972) survey data integrated with first follow-up (1973) survey data. The base-year data consist of responses to a Student Questionnaire, the results of an ability test, and information from the Student's School Record Information Form. Follow-up data consist of responses to a mailed questionnaire. The pre-machine data processing consisted of coding alphabetical information and "errors", such as partial responses or legitimate non-responses. Subsequent machine editing included range checks, consistency checks, and routing checks. There are 22,398 records in the NLS merged base-year/first follow-up data file--one record for each respondent. Each record consists of 921 variables. The data contained in each record in the file are generally grouped by type and ordered as follows: identification codes, data indicators, test battery data, student's School Record Information Form data, base-year Student Questionnaire data, First Follow-Up Questionnaire data, quality indices sampling weights, school variable data, and analytic indices. These tapes are now available for purchase from the National Center for Education Statistics. (BW)