"This bulletin proposes a new criminal justice paradigm for young men and women ages 18 to 24. Noting that the human brain has been clinically shown to not fully mature prior to the mid-20s, the authors suggest new institutional methods and processes for young adult justice that can meet the realities of life for today’s disadvantaged youth involved in crime and the criminal justice system. The authors envision a system that extends the reach of the juvenile court to reflect a modern understanding of the transition into adulthood. Their primary recommendation is that the age of juvenile court jurisdiction be raised to 21, with additional, gradually diminishing protections for young adults up to age 24 or 25." Sections include: introduction and history; why young adults are a distinct population—brain development in young adults, and the changing context of adulthood; current outcomes for justice-involved youth; implications for an age-responsive criminal justice system—pre-arrest and arrest, pretrial, courts, community-based programs, incarceration, and collateral Consequences; San Francisco Adult Probation Transitional Age Youth (TAY) Unit; Roca—a model community program for high-risk young men in Massachusetts; future facilities in New York and California; and conclusion.