Although adolescents are the primary focus of juvenile justice, a significant number of young people involved with this system are considered transition age youth (i.e., 16-25 years of age). The aim of this review is to summarize the specific needs of transition age youth with mental health conditions involved with the juvenile justice system, identify the multiple service systems relevant to this group, and offer recommendations for policies and practice. A comprehensive search strategy was used to identify and synthesize the literature. Findings highlight the paucity of research specific to transition age youth. Thus, we also summarized relevant research on justice-involved adolescents, with a focus evaluating its potential relevance in the context of the unique milestones of the transition age, including finishing one's education, setting and working towards vocational goals, and transitioning from ones' family of origin to more independent living situations. Existing programs and initiatives relevant to transition age youth with mental health conditions are highlighted, and nine specific recommendations for policy and practice are offered.