Background: Health care needs to evolve to meet the needs of people living with HIV as they age and become a more diverse population. For HIV and other conditions, physician specialty and experience are often positively associated with disease-specific outcomes but negatively associated with primary care outcomes. The objectives of this thesis were to: 1) assess comorbidity prevalence among people living with HIV in Ontario; 2) describe the type and extent of care by physician specialty; 3) use a theoretical shared primary/specialist care typology to characterize this care; 4) measure the quality of care delivered related to this typology; and 5) assess the independent effect of family physician HIV experience. Methods: Population-based data were used to describe a cohort of 14,282 individuals living with HIV in Ontario. Health care visits to this cohort were categorized by physician specialty, physician HIV experience, and HIV-related versus HIV-unrelated care. A theoretically-based typology of care was developed by linking patients to usual family physicians and to HIV specialists with 5 possible patterns of care. Prevention and chronic disease management adherence, antiretroviral (ART) prescribing, and health care utilization were compared across typology models using multivariable hierarchical logistic regression analyses. The independent effect of family physician experience was also examined. Results: People with HIV had significant comorbidity. Family physicians provided the majority of care. Five patterns of care were described: exclusively primary care (45.4%); specialist-dominated co-management (30.7%); family physician-dominated co-management (10.1%); low engagement (8.6%); and exclusively specialist care (5.3%). After adjustment, HIV patients in exclusively specialist care had lower odds of colorectal cancer screening but higher odds of receiving ART. Odds of having an emergency department visit did not differ among models. Among HIV patients seeing only family physicians, those linked to family physicians with high HIV experience were significantly more likely to receive ART than those with lower HIV experience. Discussion: People with HIV in Ontario have substantial comorbidity. A typology of shared care between family physicians and HIV specialists had a strong influence on the quality of care delivered. These findings have important policy and practice implications and support emerging evidence that multi-specialty expertise is required to address the care needs of this population.