Thirty criminal justice offenders varying in legal status, age, type of offense, and psychiatric diagnoses were subjected to an intensive 17 to 21-day group and individual confrontation with their physical, emotional, and social boundaries through high-stress outdoor activities and cooperative group living. The target behavior of the program was a reduction of antisocial, acting-out behaviors, and a replacement with prosocial, noncriminal attitudes and activities. Analysis of pre- and post-Minnesota Multiphasic Personality Inventory (MMPI) data following seven clinical scales showed that 87 percent of the offenders described themselves as being more secure and less threatened by social interaction. The second most pervasive change, as measured by the dominance-submission and sexual role identity scale, was that clients were able to integrate the more aggressive and passive aspects of their personalities. Results of 'reality testing' showed offender abilities for dealing with intrapsychic stress and the problems of daily living. Another positive finding was a greater awareness of anxiety and tension in about one-half of the patients. The majority of the patients also returned less paranoid, less suspicious, and more trusting of themselves and others. It is concluded that the MMPI data show clear evidence of dramatic personality changes that are virtually universal among offender participants and appear to be solely due to the intervening Wilderness Experience Program. One table and one chart provide data on changes in MMPI clinical scales; and medical, behavioral, legal, and demographic selection criteria for the Wilderness Experience Program are listed.