Understanding the military capabilities of both rebel groups and state counterinsurgents is fundamental to studying the dynamics of internal conflicts. Such capabilities are expected to influence the ability of rebel groups to sustain fighting and achieve particular outcomes, as well as the types and severity of violence in which those groups engage. In turn, establishing these relationships empirically depends on reliable assessments of the armed strength of rebel groups and state counterinsurgents. Assessments of rebel and state capability divide into two camps. Each camp has a different take on the role that these capabilities play in exerting coercion.