A NUMBER OF PROPOSITIONS ABOUT THE CONSEQUENCES OF IMPRISONMENT ON THE ATTITUDES AND BEHAVIOR OF INMATES ARE TESTED WITH INTERVIEW AND QUESTIONNAIRE DATA GATHERED AT A MAXIMUM SECURITY PRISON IN A SOUTHEASTERN STATE IN 1969 AND 1970. THE SAMPLE OF 276 INMATES THAT PROVIDED THE BASIS FOR THE ANALYSIS IS ACKNOWLEDGED NOT TO BE PURELY RANDOM; HOWEVER, A SERIES OF COMPARISONS OF SAMPLE STATISTICS WITH POPULATION PARAMETERS INDICATED THAT THE SAMPLE WAS REPRESENTATIVE WITH REGARD TO SUCH RELEVANT FACTORS AS OFFENSE TYPE, ETHNICITY, INSTITUTIONAL ASSIGNMENTS, AND SENTENCE LENGTH. THE OPERATIONAL MEASURES OF THE MAJOR VARIABLES ARE AS FOLLOWS: POWERLESSNESS, POSTPRISON EXPECTATIONS, NORMATIVE ASSIMILATION, SOCIAL ROLE ADAPTATION, OPPOSITION TO THE PRISON ORGANIZATION, CRIMINAL IDENTIFICATION, AND OPPOSITION TO THE LEGAL SYSTEM. THE FINDINGS FROM THE STUDY INDICATE THAT THE DEGREE OF NORMATIVE ASSIMILATION AND THE ASSUMPTION OF AN ANTISOCIAL INMATE ROLE ARE STRONGLY RELATED TO NEGATIVE ATTITUDES TOWARD THE PRISON ORGANIZATION, OPPOSITION TO THE LEGAL SYSTEM, AND CRIMINAL IDENTIFICATION. THUS, THE THEORY THAT PREPRISON, PRISON-SPECIFIC, AND EXTRAPRISON VARIABLES ARE DIRECTLY LINKED WITH THE MEASURES OF ASSIMILATION IN PRISON IS SUPPORTED. IT IS CONCLUDED THAT PRISON, PARTIULARLY MAXIMUM SECURITY, THROUGH ITS COERCION AND CONTROL STIMULATES ASSIMILATION INTO AN INMATE SUBCULTURE MARKED BY SUBSTANTIAL NEGATIVISM AND HOSTILITY TOWARD THE STAFF, PROGRAM, AND POLICIES OF THE PRISON ORGANIZATION. SUCH A HAPPENING IS BELIEVED TO UNDERMINE BOTH THE REHABILITATION AND CONTROL FUNCTIONS OF THE PRISON. DATA FROM THE STUDY ARE INCLUDED. (RCB)