This book proposes theories of SOF and irregular warfare to describe how states can use SOF to achieve strategic objectives. The theory defines special operations forces as those forces organized to combat irregulars and irregular warfare as war fought by institutionally weak combatants, as opposed to conventional warfare between institutionally strong states. A study of the evolution of irregular warfare and its theoretical underpinnings leads to five characteristics that differentiate it from conventional warfare. These characteristics define an opaque form of warfare, requiring physical, cognitive, and moral access to successfully pursue strategic objectives. The theory then proposes a set of tenets to guide operational planners and leaders in arranging SOF tactical actions to achieve a strategic objective.