This thesis investigates federalism and civil conflict. Past work linking federalism and civil conflict has investigated the factors that pacify or aggravate conflict, but most such studies have examined the effect of decentralization on conflict onset, as opposed to the form federalism takes (such as congruent vs incongruent forms, for example). I collect data on civil conflict, the institutional characteristics of federalist states and fiscal decentralization. My theoretical expectations are that federations who treat federal subjects differently than others, most commonly in an ethnically based manner, are likely to experience greater levels of conflict incidence and more severe conflict. I find support for these expectations, suggesting more ethnically based federations are a detriment to peace preservation. I close with case studies that outline three different paths federations have taken with regards to their federal subunits.