Inmate classification involves (1) assignment of inmates to appropriate custody and security levels; (2) program placement based on inmate needs and available services; (3) designation of the proper housing placement in the institution; and (4) routinely scheduled reassessment of custody and program placements, progress, and adjustment. Essential elements of classification systems are the availability and use of quality information relevant to classification decisionmaking; the basing of custody decisions on relevant past behavior; use of the least restrictive custody required to protect society, staff, and other inmates; systematic assessment of inmate needs at intake and again at reclassification; selective use of tests for psychological disturbance; provision for monitoring and preventing abuses in classification; the use of classification forms compatible with other data needs; and a standard reclassification process that addresses both custody and program needs. Data required to make rational program and security decisions for inmates are, when aggregated, the same data required to manage an institution, a region, or an entire agency. Despite the increased interest in classification, most agencies have done little to improve their classification efforts. This has been due to a general misunderstanding of the intent and capabilities of classification, little attention to implementation and training issues, failure to use classification as an integral component of overall operations, and the failure to address constraints imposed by agency policy and the political environment.