May 2009 — Fifty leading HIV-prevention experts gathered on May 13–14, 2009 to advance the development and validation of HIV incidence assays — tests that are used to identify the number of recent HIV infections in a population within a given time period. Virologists, immunologists, assay developers, industry representatives, public health scientists and epidemiologists from around the world participated in interactive, problem-solving sessions to propose how best to improve the use of current HIV incidence assays and to develop new assays, as well as to determine the global demand for these assays. The meeting was convened by FHI 360, with funding from the Bill & Melinda Gates Foundation, and support from the World Health Organization (WHO), the HIV Prevention Trials Network (HPTN), and the Center for HIV/AIDS Vaccine Immunology (CHAVI). Dr. Timothy Mastro, Director, Global Health, Population and Nutrition at FHI 360, chaired the meeting.