In this article, we formulate a theoretical framework that examines the “internal” organizational characteristics of ethnic minority political parties, the characteristics of the ethnic minority group they purport to represent, and the external environment that these parties face, to explain the political success of these parties. As an empirical plausibility probe of this framework, we use data from 1991 to 2016 for 41 ethnic minority parties across 12 countries and 89 national legislative elections. Using a logistic regression analysis, our findings suggest that party organizational capability is most associated with ethnic minority party success in postcommunist politics when compared to other “supply” and “structure of opportunity” variables.