Over the past twenty years, the developmental reform to juvenile justice has shifted law, policy, and practice toward a research-informed perspective on adolescent development. However, as with any reform, the developmental reform has vulnerabilities that may reduce its likelihood to be sustained. In order to maintain and build upon the gains of the developmental reform to juvenile justice, we document a 2-phase, 5-year effort to identify and track threats to the reform. In Phase I, a threat assessment methodology was employed to develop a consensus among a panel of experts about threats to the developmental reform and potential mitigating strategies. In Phase II, panelists completed a follow-up survey 5 years later to report the manifestation and impact of the threats they had forecasted. Overall, panelists viewed the health of the developmental reform in juvenile justice positively, particularly in its rate of progression and states’ interest in the reform. Eleven threats were identified in Phase I, but only 3 of these (Racial Bias, Fragmented Efforts, and Trends in Other Social Systems) were reported as having manifested in Phase II. Notably, many of the panelists were largely unfamiliar with new and ongoing reform-relevant research, pointing to an opportunity for reform-minded researchers to disseminate their findings among policymakers and practitioners. In addition to offering a perspective on the developmental reform, the threat assessment methodology used in the project offers potential for threat assessments to forecast future trends in other public policy reforms. We close with recommendations for sustaining the progress of the developmental reform movement.