The purpose of What Works for Women and Girls: Evidence for HIV/AIDS Interventions is to provide the evidence necessary to inform country-level programming. What Works is a comprehensive review, spanning 2,500 articles and reports with data close to 100 countries, that has uncovered a number of interventions for which there is substantial evidence of success: from prevention, treatment, care and support to strengthening the enabling environment for policies and programming. What Works also highlights a number of gaps in programming that remain.