RESULTS CONTRAST WITH EARLIER, CROSS-SECTIONAL STUDIES. THE MAJOR QUESTION CONCERNS THE DIFFERENTIAL EFFECTS OF VARIOUS INSTITUTIONS ON THE ACQUISITION OF PRISON CULTURE. DATA WERE COLLECTED FROM PRISONERS ADMITTED TO THE WASHINGTON STATE PRISON SYSTEM BETWEEN JUNE AND SEPTEMBER 1974. SOCIO-LEGAL BACKGROUND INFORMATION WAS OBTAINED BY INTERVIEWS, INCLUDING A SET OF ITEMS DESIGNED TO MEASURE PRISONIZATION, WHICH WAS ADMINISTERED TO STAFF AS WELL. A TOTAL OF 198 PRISONERS WERE INTERVIEWED FOR FOLLOW-UP DATA IN FEBRUARY 1975. THE PRISONERS WERE PLACED IN THREE INSTITUTIONAL SETTINGS: THE PENITENTIARY, ACCEPTING THE TOUGHEST, MOST HARDENED CRIMINALS; THE REFORMATORY, ACCEPTING YOUNGER FELONS WITH LESS SERIOUS CRIMINAL INVOLVEMENT; AND THE CORRECTIONS CENTER, ACCEPTING THOSE WHO COULD BENEFIT FROM REHABILITATION PROGRAMS. THESE INSTITUTIONS WERE USED AS THE INDEPENDENT VARIABLE IN ANALYZING RESPONSES TO THE TWICE-ADMINISTERED PRISONIZATION QUESTIONS (THE DEPENDENT VARIABLE). FINDINGS SUGGEST THAT PRISONERS FROM VARIOUS BACKGROUNDS, WITH VARIED EXPERIENCES, AND WITH DIFFERENT LEVELS OF PRISONIZATION UPON ENTERING THE SYSTEM, ALL BECAME MORE PRISONIZED, AND CHANGED TO AN EQUAL LEVEL WITHIN 6 MONTHS INCARCERATION, REGARDLESS OF INSTITUTIONAL ASSIGNMENT. THESE RESULTS CONTRAST WITH EARLIER STUDIES, WHICH SUGGESTED THAT CUSTODY-ORIENTED INSTITUTIONS HAVE A STRONGER EFFECT ON PRISONIZATION THAN TREATMENT-ORIENTED PRISONS. HOWEVER, THESE PRIOR STUDIES COMPARED PRISONERS FROM DIFFERENT INSTITUTIONS WITHOUT CONTROLS FOR ATTITUDES. OVERALL THIS STUDY CASTS DOUBT ON MANY OF THE CONCLUSIONS OF CROSS-SECTIONAL RESEARCH AND ENCOURAGES LONGITUDINAL RESEARCH DESIGNS. TABLES AND FOOTNOTES ARE INCLUDED. THE PRISONIZATION ITEMS OF THE QUESTIONNAIRE, STAFF RESPONSES TO THEM, AND REFERENCES ARE APPENDED. (MRK)