Despite their alleged anti-systemness and 'non-coalitionability', radical right and radical left parties have, since the early 1990s, both supported and entered coalition governments in a number of European liberal democracies. Using the classical 'size and ideology' framework, this study sets out to examine how-or, put differently, under what circumstances-radical right and radical left parties are able to overcome the obstacles associated with governing and enter coalition governments. Inspired by previous observations regarding the complex and multicausal nature of radical government participation, the study relies on a configurational method. By means of a fuzzy-set qualitative comparative analysis (fsQCA) of 37 radical parties at 207 coalition formation instances in 22 (Western and Central and Eastern) European countries, the article sheds light on different paths that lead to government inclusion (and exclusion) of radical actors. The empirical evidence indicates that electoral success in combination with a fairly similar policy position to a weak prime minister party is sufficient for government inclusion. The paths to government exclusion, by contrast, underline the importance of ideological distance in combination with size-related factors.