This article analyses the factors shaping the implementation of local participatory institutions (LPI) using evidence from Chile's 345 communes. Based on the literature on participatory politics, it identifies several factors associated with the implementation of LPI, which are categorised into two dimensions: municipal supply vs. civic demand, and capacity vs. agency. Regression analyses show that explanations emphasising social structure, and to a lesser extent, municipal capacity, have more explanatory power than the ones emphasising municipal and social agency. Specifically, municipal financial and professional capacity, and local poverty and population size have important effects on LPI implementation.