This paper provides a description and analysis of morphological causative constructions in Kirundi. I show that the causative inter- pretation of Kirundi’s two causative suffixes, -i and -ish, can be explained by a single syntactic structure. To do so, I demonstrate that the phonological and syntactic properties of -ish causatives re- quire a bimorphemic account wherein the suffix is derived from two functionally different heads: an unaccusative v head embedded by a higher Causative head. I present new empirical data collected from fieldwork in order to support these claims and fill a gap in the exist- ing documentation of the argument structure of Bantu causatives. In addition to presenting a singular account of Kirundi causative syn- tax, the proposal sheds light on cross-linguistic variation in the struc- ture of v/Voice and valency-effecting morphology, with implications for formal typologies of causatives.