Long‐term imprisonment often results in negative psychological and behavioural effects that hinder effective reintegration into society, exacerbating antisocial behaviour and increasing recidivism rates. In response to a Supreme Court mandate, California, the state with the second‐largest prison population in the United States, embarked on a significant prison downsizing initiative. Designed to help violent offenders develop emotional intelligence, mindfulness, and understanding of victim impact, Guiding Rage into Power (GRIP) is an example of a rehabilitation program expanding within California's state prison system in part because it has generated promising results. Building on previous investigations of the same program, this study evaluates the effectiveness of GRIP in altering incarcerated men's self‐perceptions and observed behaviours, with a focus on trust and self‐control. Employing a mixed‐methods approach, including a qualitative photo elicitation task and psychological scales, data were collected from GRIP and non‐GRIP participants in two California prisons. GRIP participants demonstrated a profound commitment to self‐awareness and transformation, as evidenced by their narratives and photo choices. Differential levels of trust between the two groups also predicted distinct outcomes in the photo elicitation task. While this study has limitations, it underscores GRIP's potential to challenge entrenched identities and foster positive internal changes, paving the way for future research to assess broader program impacts. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement.