Worldwide, patterns of violence against women differ markedly from violence against men. For example, women are more likely than men to be sexually assaulted or killed by someone they know. The United Nations has defined violence against women as "gender-based" violence, to acknowledge that such violence is rooted in gender inequality and is often tolerated and condoned by laws, institutions, and community norms. Violence against women is not only a profound violation of human rights, but also a costly impediment to a country's national development. While gender-based violence occurs in many forms throughout the life cycle, this review focuses on two of the most common types-physical intimate partner violence and sexual violence by any perpetrator. Unfortunately, the knowledge base about effective initiatives to prevent and respond to gender-based violence is relatively limited. Few approaches have been rigorously evaluated, even in high-income countries. And such evaluations involve numerous methodological challenges. Nonetheless, the authors review what is known about more and less effective-or at least promising-approaches to prevent and respond to gender-based violence. They present definitions, recent statistics, health consequences, costs, and risk factors of gender-based violence. The authors analyze good practice initiatives in the justice, health, and education sectors, as well as multisectoral approaches. For each of these sectors, they examine initiatives that have addressed laws and policies, institutional reforms, community mobilization, and individual behavior change strategies. Finally, the authors identify priorities for future research and action, including funding research on the health and socioeconomic costs of violence against women, encouraging science-based program evaluations, disseminating evaluation results across countries, promoting investment in effective prevention and treatment initiatives, and encouraging public-private partnerships.