Book excerpt: The events, and aftermath, of September 11, 2001 brought into sharp relief the importance of violent extremism and insurgency practiced by alQai'da and its affiliates. These phenomena continue to impact parts of the Middle East, South Asia, and sub-Saharan Africa, among other regions. While alQai'da and its affiliates pose the greatest direct threat to the United States, violent extremism and insurgency practiced by other actors and motivated by other ideologies - such as the FARC in Colombia - are challenges in numerous developing countries. The drivers and effects of violent extremism and insurgency vary across context.While intertwined with political and security dynamics, many of the drivers of violent extremism and insurgency are development challenges. Indeed, factors such as socioeconomic inequalities, repression, corruption, and poor governance often create an enabling environment for radicalization and violent extremism.Informed by USAID's decades of experience in conflict affected countries, a growing body of knowledge, evidence, and practice is emerging from USAID's development efforts to counter violent extremism and insurgency. It affirms that effective development responses to these phenomena target specific factors in specific settings based on sound development principles and in a manner consistent with the USG's broader promotion of universal values, including democracy and human rights.This policy, consistent with USAID Forward principles, provides USAID with guidance on the development response to violent extremism and insurgency by:- outlining key concepts, drivers, and development responses;- elaborating specific engagement criteria and programming principles; and- identifying institutional enhancements to support USAID's development role.