Objectives: This study's main goal was to assess the efficacy of a structured cognitive-behavioral group program, Growing Pro-Social (GPS), in reducing anger, paranoia and external shame in male prison inmates.Methods: In this randomized trial, a treatment group (n=24) was compared to a control group (n=24) and both groups were assessed at pre-and post-treatment. Participants answered the State-Trait Anger Expression Inventory, the Paranoia Scale, and the Other as Shamer Scale.Treatment effects were tested using ANCOVA with baseline as covariate and condition as fixed factor. Additionally, in order to assess significant clinical change after intervention, the Reliable Change Index (RCI) was computed.Results: At baseline, no significant differences between conditions were found. ANCOVA with baseline as covariate showed significant differences between groups at post-treatment. When compared to controls, treatment subjects showed lower scores in anger-trait (temperament and reaction subscales) and paranoia. Concerning clinical change, a high percentage of treatment subjects presented improvements in anger, paranoia and external shame; the majority of controls showed significant deterioration in the same variables. After treatment, differences between groups were observed in the distributions by clinical change categories for anger-trait and its subscales, and paranoia. No differences between groups were found in anger-state and external shame.Conclusions: These results point out the GPS's ability to promote significant change in cognitive and emotional relevant variables associated with antisocial behavior.Keywords: Anger; Antisocial Behavior; Clinical Change; External Shame; Growing ProSocial; Paranoia Running head: CLINICAL CHANGE IN ANGER, SHAME, AND PARANOIA 3 Clinical change in anger, shame and paranoia after a structured cognitive-behavioral group program: Early findings from a randomized trial with male prison inmates Meta-analytic research (Andrews et al., 1990; Garret, 1985; Lipsey, 1995; Lipsey & Wilson, 1998; Lösel, 1995; McGuire 2001;Redondo et al., 1997;Redondo et al., 1999) has shown that multimodal programs have a significant impact in the reduction of recidivism in offenders. These studies pointed out that cognitive-behavioral based programs are among the most effective, namely when cognitive variables are included as targets for change (Bogestad et al., 2009; Hollin et al., 2013;Pearson et al., 2002;Wilson et al., 2005). It has been suggested that these interventions can be improved in order to achieve even better outcomes in recidivism reduction obeying to the Risk-Need-Responsivity (RNR) model (Andrews & Bonta, 2010a, b;Andrews et al., 2006;Andrews & Dowden, 2005; Dowden & Andrews, 2000, 2004. The RNR model is based in "human service principles", which state that recidivism reduction should be achieved through some type of treatment instead of punishment. Research has shown that punitive strategies actually increase criminal recidivism (Andrews & Bonta 2010a, 2010b Caldwell & R...