Justin Hummer is an associate behavioral and social scientist at the RAND Corporation. Also a clinical psychologist, he has expertise in evidence-based psychological treatments for addictive behaviors and mental health in adolescents and young adults. His research focuses on better understanding and treating problematic substance use using an ecological framework that emphasizes relevant developmental, familial, social, and cultural contexts. Hummer’s work explores individual-difference factors and mechanisms of change involved in the efficacy of health interventions delivered through digital platforms. He has additional interests in issues pertaining to psychological health among active dutyservice members and young adult veterans and in evaluating access to and quality of behavioral health care within the military health system. Hummer holds a Ph.D. in clinical science from the University of Southern California and completed his predoctoral internship at the VA Sacramento Healthcare System where he focused on rotations in empirically-supported interventions for general mental health, addiction recovery and treatment services, posttraumatic stress disorder, and behavioral medicine.