In our studies with people incarcerated in prison, we employ diagnostic clinical assessment instruments, self-report measures, and neuropsychological testing to examine the psychological mechanisms underlying of a number factors that relate to involvement with the judicial system (e.g., psychopathic and antisocial personality traits, history of childhood trauma and post-traumatic stress disorder, drug and alcohol use). We also conduct clinical trials to determine the feasibility and efficacy of psychotherapy in the prison setting. In addition, we utilize self-report questionnaires and focus groups to combine quantitative and qualitative methods in order to learn from incarcerated individuals about their needs and preferences for mental health care and treatment methods in prison.