The ability of the poor to act collectively plays an important role in the political economy of development literature, particularly on whether political institutions with electoral accountability are more likely to reduce poverty than those without. This paper suggests that ethnic divisions of the poor could explain why electoral accountability sometimes fails to improve poverty outcomes. That is, higher ethnic divisions of the poor reduce the likelihood that they will collectively act and pressure their government via electoral system to provide services that benefit them. Indonesia is a unique case to test this hypothesis because the way its districts transitioned to direct elections could be considered exogenous. Due to the unique research design, this paper aims to assess and measure the causal effects of ethnic diversity of the poor on electoral accountability and poverty outcomes.