This dissertation documents the evolution, outcomes, and replicable framework of the Justice Ambassadors Youth Council (JAYC), a criminal legal system intervention based in NYC invested in transforming not only the pathways of its participants, but also the broader relationships they hold to each other, to their communities, and to the political and institutional structures that inform their lives. I first outline the critical gap in the United States’ criminal legal system in which those who are most impacted by the realities of mass incarceration (e.g., Black and Hispanic men) are often the least represented in developing and/or enacting related policies and laws. Next, through a review of interdisciplinary academic literature, I discuss the challenges and possibilities of contact-based interventions that bring together individuals from different group memberships (specifically to JAYC, youth participants impacted by the criminal legal system and government representatives acting on the system’s behalf) for not only reducing intergroup prejudice, but also providing necessary resources to bolster individual skill-building and agency and opening up new avenues for social change engagement. In the following chapters, I discuss the founding and development of the JAYC program and highlight the many successful outcomes it demonstrates across multiple levels of change (inclusive of individual, relational, and structural-interactive outcomes). Then, in a comprehensive qualitative study that thematically analyzes 58 JAYC participant interview responses, I demonstrate how nine essential components of the JAYC program are mechanistically related to these three levels of outcomes. Finally, I document - via a recently published, first-author peer-reviewed journal article - how the JAYC program, by encompassing a human development / ecological approach to resiliency that considers the reciprocal importance of community and societal resources - can serve as a powerful model as an intervention capable of creating transformative change across a variety of contexts.