Focusing on HIV and cardiometabolic diseases (diabetes, high blood pressure, and cardiovascular disease) in low- and middle-income countries, this talk will discuss research that uses: i) nationally representative cross-sectional surveys to assess unmet need for care in a population and define suitable target groups for public health interventions; and ii) pragmatic randomized trials and quasi-experiments to assess the causal effect of health services interventions on patient and population health.