This study will evaluate the safety and efficacy of solid organ transplantation in people with HIV infection by following a prospective, multi-center cohort of HIV infected people who undergo kidney or liver transplantation. The long-term goals are: 1) to provide patients and clinicians with information regarding the HIV-specific risks of transplantation; 2) to provide clinicians with information necessary to manage immunosuppressive and HAART medications together; and 3) to understand underlying basic science mechanisms that explain patient outcomes so that clinical management can be adjusted to improve outcomes.