Although prisons are among the largest public institutions in the United States, research on life inside them, informed by people experiencing incarceration, is distinctly absent. What public knowledge exists about people who are incarcerated in prisons and those who work in them comes from the media, human rights groups, personal activism, and correctional data; people’s lived experiences in prisons, however, are broadly concealed. Consequently, policymakers, practitioners, and researchers remain disturbingly unaware of the conditions that millions of people who are held in these institutions experience and of their ideas for improving the system. To accurately and effectively address this gap, we turn to participatory methods whereby research is created with and for the people most directly affected by the conditions being studied. This brief describes the key elements of a participatory approach, explores its utility in past prison research, and identifies opportunities for using it in future research on and in correctional settings, and is part of a larger research agenda for the Prison Research and Innovation Initiative—a five-year effort to leverage research and evidence to shine a much-needed light on prison conditions and pilot strategies to promote the well-being of people who live and work behind bars.