The organizational structures of armed groups, whether they develop by accident or by design, affect their strategic choices during the conflict and their ability to enter peace agreements. This article explains how frequently encountered structures such as centralized, decentralized, networked, and patronage-based ones affect strategic choices for the organization and its opponents. Only centralized organizations can make use of sophisticated strategies such as 'divide and conquer', 'co-option', and 'hearts and minds', and can engage in successful peace agreements. Centralized armed organizations that do not have a safe haven within the contested territory tend to be very vulnerable, however, which makes peace less attractive to their opponents and explains in part why long-lasting peace agreements between such groups and their opponents are rare.