As research linking childhood and youth experiences to adult health status has evolved, two subpopulations—youth in child welfare and juvenile justice systems—have become the primary focus of policy and practice reform. Recent research, however, suggests we may be paying too little attention to a third and perhaps more vulnerable group—youth with histories in both the child welfare and juvenile justice systems, also referred to as “crossover youth.” Over the past decade, the Sierra Health Foundation has invested in community efforts to improve the health and well-being of youth. As they focused efforts around juvenile justice, the foundation believed it to be a critical and opportunity-laden moment in which a regional funder could influence juvenile justice policy and practice across the entire state and perhaps the nation.