This manual will familiarize data users with the procedures followed for data collection and processing of the base-year teacher component of the National Education Longitudinal Study of 1988. A corollary objective is to provide the necessary documentation for use of the data files. The manual provides a wide range of information on topics related to the National Center for Educational Statistics (NCES) and the study at hand. More specifically, the report includes an overview and history of NCES longitudinal studies, a general description of the data collection instruments used in the 1988 base-year study, the base-year sample design and procedures used for selecting teachers, data collection procedures as well as schedules and results, data control and data preparation activities, data processing, organization and content of the data files and means of using them, guidelines for the Statistical Analysis System and Statistical Package for the Social Sciences, and several code books of teacher questionnaire data. The target sample included 1,052 schools. Self-administered questionnaires and tests were the principal mode of data collection. The NELS:88 base-year study collected data from students, parents, teachers, and school administrators. The NELS:88 public use data files are available on four separate tapes, one for each study component. The tape for the teacher survey contains a data file based on 5,193 teacher instruments, resulting in 44,512 sets of teacher ratings and data for 23,188 of the 24,599 participating students from 1,052 schools. Seven figures and four data tables are included. Appendices include: the teacher instrument, a record layout for the teacher questionnaire, a list of critical items in the teacher questionnaire, specifications for the composite variables, and a description of related data files available from NCES. (TJH)