This manual familiarizes data users with the procedures followed for data collection and processing of the high school transcript component of the National Education Longitudinal Study of 1988 (NELS:88). A second objective is to provide the necessary documentation for using the data files. Chapter 6 and appendix F, in particular, contain information that will allow the user to incur minimal startup cost. The rest of the manual provides a wide range of information on NELS:88. Chapter 1 gives an overview of the study. Chapter 2 contains a description of the data collection materials and procedures. Chapter 3 documents sample design and weighting procedures, while chapter 4 concentrates on data control and preparation. Data processing, including the conversion of transcript data to machine-readable form, machine editing, and construction of the merged, clean data tapes is described in chapter 5. In addition to startup information, chapter 6 describes the organization and contents of the data files and provides important suggestions for using them. The 16 appendixes provide a wealth of supplemental information, including: transcript survey data collection materials; grade conversion scales; NELS:88 Transcript Data weights, flags and composite variables; codebooks for the transcript component; glossary of NELS:88 terminology; and a list of NELS:88 publications. Four figures and 11 tables in the text illustrate the discussion. (SLD)