In Haro, an Omotic language of Ethiopia, participants are encoded both on nouns as well as verbs. The principal strategy used to mark participants is by way of morphology. Apart from Agents and Patients (or Goals), noun phrases with Dative, Comitative, Instrumental and Ablative roles are identified by morphological ways. One remarkable feature concerning participant marking in Haro is that this system closely interacts with definiteness marking. An indefinite noun cannot undergo a morphological marking for subjecthood or objecthood. Hence, with indefinite nouns, constituent order remains to be the only means to identify who did what to whom. One other remarkable property of the system is that it closely interacts with focus marking. Participants within a focus domain are marked distinctively from those outside a focus domain.