After more than a decade of combating Al Qaeda in Afghanistan and Pakistan, the United States now faces an increasingly diverse threat from Al Qaeda affiliates in the Middle East and Africa and from emerging groups that have adopted aspects of Al Qaeda's ideology but operate relatively or completely autonomously from the group's senior leadership. U.S. counterterrorism debates have focused on "formal" Al Qaeda affiliates, and policymakers increasingly are considering options for addressing the range of threats posed by the wider spectrum of groups inspired by—or similar in goals and aspirations to—Al Qaeda. This book examines Al Qaeda-affiliated groups in the Middle East and Africa, as well as the "Islamic State", and Nigeria's Boko Haram.