Through its Targeted HIV Outreach and Intervention Model Development (Outreach Initiative), the Health Resources and Services Administration's Special Projects of National Significance (SPNS) program funded ten demonstration sites to implement and evaluate strategies to engage and retain underserved populations living with HIV/AIDS (PLWHA) in HIV primary medical care. The 10 sites were located in urban areas across the United States. Target populations were women, youth, people of color, and people with histories of incarceration, substance use, homelessness, or mental illness. Program interventions included outreach, motivational interventions, case management, and other ancillary services to connect and sustain people in HIV medical care. To evaluate outcomes from this initiative, a multisite study consisting of client interviews administered at 6-month intervals, documentation of program contacts, and medical chart abstractions of CD4 and viral load values and HIV primary care visits was conducted. This paper describes the study design and methods used to implement and evaluate this large multisite initiative. Strengths and limitations of the study design are discussed.