Four therapy groups, a pretest and no pretest control group were compared on expressed willingness to engage in prosocial behavior as measured by a Likert-type rating scale. The treatment groups scored significantly higher than no treatment controls (p < and p <). The four types of therapy were Gestalt therapy, Reality therapy, Rational-Emotive therapy (RET) and Friendship therapy which was developed by this experimenter. The experimental hypothesis that participants (prison inmates) receiving treatment would score significantly higher than those who received no treatment was supported. The expectation that participants whose therapy involved a prosocial action component (Friendship therapy) would score significantly higher than other treatment groups was not supported. No significant differences were found between treatment groups. Ancillary measures which were qualitative in nature included participants' statements regarding their therapy. These were unequivocally positive. Staff comments regarding behavior of participants in the therapy groups were equivocal in that participants who broke with regular routine to attempt to engage in prosocial behavior tended to receive the least favorable comments. Quantitative measures suggest that any therapeutic intervention will have small but significant positive effects on expressed willingness to engage in prosocial behavior. Qualitative measures suggest that the prison setting may inhibit and be antithetical to the development and sustainment of prosocial behavior. The direction of future research must be toward development of more sensitive instruments and research designs in the service of providing clinicians with correct behavioral tools for adapting the scientist practitioner tradition to correctional settings. Longitudinal studies will be necessary and incentives for prosocial behavior are recommended to reduce the public health threat posed by crime and violence. N = 108 adult, male, maximum and close security state prison inmates; n for each treatment and control group = 18. (PsycINFO Database Record (c) 2016 APA, all rights reserved)