This research complements improvements in HIV services being developed in San Francisco under the auspices of the CDC’s Enhanced Comprehensive HIV Prevention Planning (ECHPP), and augments ECHPP-related evaluations already being supported through the NIH-supported Centers for AIDS Research. It involves three partnering organizations – the UCSF Center for AIDS Prevention Studies (CAPS), UCSF Positive Health Program (PHP), the San Francisco Department of Pub lic Health (SFDPH), all three of which are units with the GIVI UCSF Center for AIDS Research (CFAR). Specifically the aims of the study are: (1) to determine the outcomes among patients at the PHP who have been lost to follow-up and, for those who are shown to be out of care, to assess the feasibility and acceptability of potential strategies for re-engaging them in care at the UCSF PHP; (2) to match patients lost to follow-up at the PHP with surveillance system records to determine the proportion that show evidence of receiving care elsewhere; and (3) to identify potential intervention strategies to enhance re-engagement and retention in HIV care among at risk patient populations at PHP. Aim 1 will be accomplished by tracking and surveying 150 PHP patient s who have been lost to follow-up to understand the reasons they are no longer receiving services at PHP (e.g., in care elsewhere, fallen out of care completely) and, then, by conducting in-depth qualitative interviews with up to 30 of those patients who h ave fallen out of care completely to understand the feasibility of potential strategies to help retain and re-engage them in care. For Aim 2, we will link our tracking data with records at the surveillance section of DPH to determine if the surveillance system contains evidence of the same patients having received care elsewhere in the city (e.g., viral load or CD4 testing). The findings from this aim will allow us to examine the degree to which surveillance records can supplement clinic based efforts to determine patients’ engagement-in-care outcomes and identify which tracking efforts/elements were most beneficial. Finally, for Aim 3, we will convene a consensus development panel with representatives of the three partnering institutions – CAPS, PHP Ward 8 6, SFDPH – to identify behavioral interventions that could enhance retention and re-engagement in care among at risk patient populations in San Francisco that utilize the PHP for HIV care.