The model prison in Lucknow, Uttarp Dradesh, was established in 1949 for the purpose of embodying the most advanced penal theories. Program emphasis is on classification, education, occupational training, and self-sufficiency. Data were gathered in 1973 and 1974 from observation of inmates and custodians, formal and informal interviews with inmates and prison personnel, examination of individual files of inmates, official publications and reports of the office of Inspector General of Prisons, and procedures and regulations issued by the model prison. Subjects covered are the formal and informal structures of the prison; communication, cooperation, and conflict among custodian and between custodians and inmates; elements of prison culture; and external influences on the prison. Results show that the inmate culture is like a caste system, a rigidly hierarchial system where vertical mobility is possible but difficult. The violent inmates who are adept at intimidation and the use of physical force are at the top, while the sex offender and the petty thief are at the bottom of the status ladder. Although the formal structure for prison life presents a facade of inmate control, the informal inmate system has the most direct control over inmate behavior, with trustees (convict overseers and convict warders) having the most power. The internal peace of the prison depends essentially on inmates' cooperation with prison personnel, and the formal hierarchy generally tends to use the inmate power structure as an aid in prison administration. Informal controls depend on intimidation, and authority is used to exploit inmates. Inmate adaptation to the prison culture is basically debilitating and a response to coercion, such that formal prison efforts to modify behavior have been futile. Tabular and graphic data, an index, and over 150 references are provided.