This data collection, conducted in a federal penitentiary and prison camp in Terre Haute, Indiana, between September 1986 and July 1988, was undertaken to examine the reliability and validity of psychological classification systems for adult male inmates. The classification systems tested were Warren's Interpersonal Maturity Level (I-level), Quay Adult Internal Management Systems (AIMS), Jesness Inventory, Megargee's MMPI-Based Prison Typology, and Hunt's Conceptual Level. The study sought to answer the following questions: (a) Which psychological classification systems or combination of systems could be used most effectively with adult populations? (b) What procedures (e.g., interview, paper-and-pencil test, staff assessment, or combination) would assure maximum efficiency without compromising psychometric precision? (c) What could the commonalities and differences among the systems reveal about the specific systems and about general classification issues pertinent to this population? and (d) How could the systems better portray the prison experience? The penitentiary was a low-maximum-security facility and the prison camp was a minimum-security one. A total of 179 penitentiary inmates and 190 camp inmates participated. The study employed both a pre-post and a correlational design. At intake, project staff members interviewed inmates, obtained social, demographic, and criminal history background data from administrative records and test scores, and then classified the inmates by means of an I-level diagnosis. Social and demographic data collected at intake included date of entry into the prison, age, race, marital status, number of dependents, education, recorded psychological diagnoses, occupation and social economic status, military service, evidence of problems in the military, ability to hold a job, and residential stability. Criminal history data provided include age at first nontraffic arrest, arrests and convictions, prison or jail sentences, alcohol or drug use, total number and kinds of charges for current offense, types of weapon and victims involved, co-offender involvement, victim-offender relationship, if the criminal activity required complex skills, type of conviction, and sentence length. T-scores for social maladjustment, immaturity, autism, alienation, manifest aggression, withdrawal, social anxiety, repression, and denial were also gathered via the Jesness Inventory and the MMPI. Interview data cover the inmates' interactions within the prison, their concerns about prison life, their primary difficulties and strategies for coping with them, evidence of guilt or empathy, orientation to the criminal label, relationships with family and friends, handling problems and affectivity, use of alcohol and drugs, and experiences with work and school. For the follow-up, the various types of assessment activities were periodically conducted for six months or until the inmate's release date, if the inmate was required to serve less than six months. Data collected at follow-up came from surveys of inmates, official reports of disciplinary infractions or victimizations, and prison staff assessments of inmates' prison adjustment and work performance. The follow-up surveys collected information on inmates' participation in treatment and educational programs, work absenteeism, health, victimization experiences and threats, awards, participation in aggressive, threatening, or other illegal activities, contact with family and friends, communication strategies, stress, sources of stress, and attitudes and beliefs about crime and imprisonment. Follow-up ratings by prison staff characterized the inmates on several clinical scales, according to each rater's global assessment of the interviewee. These characteristics included concern for others, role-taking abilities, assertiveness, inmate's relations with other inmates, authorities, and staff, verbal and physical aggressiveness, emotional control under stress, cooperativeness, need for supervision, response to supervision, maturity, behavior toward other inmates, and behavior toward staff.