The USAID Health Care Improvement Project (HCI) and Tanzania’s Ministry of Health and Social Welfare (MOHSW) implemented an improvement collaborative aimed at improving the quality of HIV services and health worker performance in 12 health care facilities in Tandahimba District starting in June 2010. Tandahimba is one of six districts in the Mtwara Region, where a larger improvement collaborative to improve clinical processes related to antiretroviral therapy (ART) and prevention of mother-to-child transmission of HIV (PMTCT) had started in September 2009. The goal of the Tanzania HIV Care and Health Worker Performance Improvement Collaborative was to improve the efficiency of service delivery for patients receiving services related to HIV and to strengthen the performance and engagement of health workers providing HIV services.