Data for the analyses were obtained from the Computerized Criminal History/Offender-Based Transaction Statistics data system (CCH/OBTS) maintained by the Division of Criminal Justice Services, supplemented by data from the Indictment Statistical System (ISS), which tracks felony prosecutions from indictment through sentencing. The study analyzes a 1980 disposition 'cohort' of 104,579 cases -- all adult felony arrest events between January 1, 1971, and December 31, 1980, which were disposed during calendar year 1980. The 'arrest event' is the unit of count used in most of the report. This consists of all charges placed against an offender for a given arrest, although only the most serious charge is counted for the analysis. Concerning the validity of the OBTS data, a comparison with an arrest-based file representing the population of all cases without regard to missing dispositions indicates that the OBTS file adequately represents all New York State felony arrests. Definitions for core terms in the report are presented, followed by brief explanations for missing data and magnitudes of observed relationships. The appendixes examine the validity of the OBTS data and the selection of charge and disposition for analysis. For other volumes in the report, see NCJ 93256-57.