Electoral rules have long been held as important for the success of new political parties, but research has neglected the dimension of territory in this equation. This article argues that the territorial structure of social groups, in interaction with the electoral system, makes a crucial difference for the ability of new parties to enter parliament. In district-based electoral systems, social groups that are highly concentrated face much lower hurdles with an own party than groups that are spread throughout the country. The argument is tested on a novel database on ethnic minority groups from post-communist countries in Europe, including 123 minorities in 19 countries. To test hypotheses with complex interaction effects and binary variables, Qualitative Comparative Analysis appears as the most suitable method. After controlling for size and special minority-relevant provisions in the electoral systems, there is strong confirmation for the hypothesised effect.