More and more Western European radical right‐wing populist parties participate in the governments of their respective countries. At least some of these parties moderate—that is, become less radical—once they join the government; others, however, do not. Although the literature has addressed such moderation, the conditions that lead to it have not been analyzed comprehensively. In this paper, we use a fuzzy‐set qualitative comparative analysis (fsQCA, N = 14) to determine what conditions are consistently associated with moderation across cases. We find that the degree of governmental responsibility a party takes over is as important as its internal dynamic. In a ruling coalition, compromises must be found, which can create high internal tensions within the radical right‐wing populist party. Joining government can thus have its price: a crisis of party identity and a strong compulsion to moderate.