After presenting a basic definition and conceptual overview of offender needs assessment, the manual identifies essential criteria for an effective needs assessment system. Principles for an effective needs assessment system focus on the system's overall design and the quality of needs assessment methods. An overview of current national needs assessment practices addresses the scope and results of the survey conducted and the four clusters of State systems found. The more systematic and objective needs assessment programs are then described in detail. These include (1) the National Institute of Corrections model used in Kentucky and Wisconsin, (2) models used in Washington and Oklahoma, (3) the Correctional Classification Profile used in some States, and (4) the model used in the Federal prison system. Current practices and resources for assessing specific offender needs are reviewed. These encompass needs related to health, mental health, alcohol/drug abuse, intellectual/adaptive behavior, academic education, vocational aptitude and interests, job skills, personal-social skills, family and friend relationships, and victimization potential. Other issues addressed are needs assessment for female offenders, ethical issues in psychological assessment, and assessment for internal-management classification. Appendixes contain offender assessment instruments, descriptions of alcohol/drug abuse screening instruments, a list of publishers of assessment instruments and contact persons for participating systems, and survey results. Approximately 90 references are listed.