Findings are reported for why 17-year-olds should be in juvenile court: their brain development, behavior, and the law; safety benefits; and economic benefits. An analysis is also presented regarding the impact of raising the age in Illinois: predicted effect; impact of raising the age for misdemeanors; eight steps for registering system responses to jurisdiction change—investigation and arrest, diversion programs and community-based services, prosecution/court proceedings/plea arrangement, detention, probation, sentencing, incarceration, and recordkeeping and expungement; and the broader themes of disproportionality and discretion, clear guidelines for implementation, and transfer and accountability. “To promote a juvenile justice system focused on public safety, youth rehabilitation, fairness, and ?scal responsibility, Illinois should immediately adopt legislation expanding the age of juvenile court jurisdiction to include 17-year-olds charged with felonies … It is counterproductive and cruel to impose the lifelong collateral consequences of felony convictions on minors who are likely to be rehabilitated. Illinois can achieve better long-term outcomes for 17-year-olds, public safety, and the state economy by expanding juvenile jurisdiction. In doing so, it is critical to ensure the juvenile justice system is robust, by adequately funding and supporting diversion, probation, and community-based services, as well as the public educational, health, and human service infrastructure upon which many at-risk youth must rely. E?orts at reducing the extent of youth contact with the juvenile justice system by focusing on front-end services are working; in order to be most e?ective, however, these services must be fully-funded, available, and extended through all developmentally-appropriate ages” (p. 60).