Bosnia and Herzegovina (BiH) is referred to as a complex state featuring 13 constitutions and 1 statute. Several levels of government, including the state level and substate levels (Entities and cantons) enjoy different degrees of power and consequently different degrees of institutional autonomy. On top of this, the constituent power is vested in the constituent peoples (Bosniaks, Croats, and Serbs). The principles of parity and proportional representation of the constituent peoples are the key ingredients of BiH’s ethno-territorial set-up and one of the main causes of deadlocks in decision-making processes. Coordination as an instrument and mechanism is introduced in the constitutional framework to tackle some of these issues; however, it seems that it is poorly understood and underused. Also, given that the ethno-territorial fault-lines are reinforced by ethnic political parties, coordination efforts have been interrupted by diverse political agendas of ethnic political leadership. This chapter looks into the intergovernmental relations in BiH and how they reflect on horizontal intergovernmental coordination in BiH, especially through the lens of mutual and coordinative agreements. The chapter also looks into the role of the European Union (EU) accession process in coordinating activities in BiH.