Lovejoy’s research interests include the scientific development, testing, and implementation of theory-based clinical and health services interventions that improve individual and population health. Current lines of research examine novel treatment approaches for chronic pain in patients with co-occurring substance use disorders and HIV prevention in older adult populations. Lovejoy’s research approaches include large retrospective administrative database studies, clinical and health services efficacy and effectiveness trials. He also researches mixed methods approaches to study the implementation of evidence-based practices. Lovejoy is the lead of the Implementation Science Core in the Center to Improve Veteran Involvement in Care at the VA Portland Health Care System.