What explains the cross-national variation in the radical right's electoral success over the last several decades? Challenging existing structural and institutional accounts, this book analyzes the dynamics of party building and explores the attitudes, skills, and experiences of radical right activists in eleven different countries. Based on extensive field research and an original data set of radical right candidates for office, David Art links the quality of radical right activists to broader patterns of success and failure. He demonstrates how a combination of historical legacies and incentive structures produced activists who helped party building in some cases, and doomed it in others. In an age of rising electoral volatility and the fading of traditional political cleavages, Inside the Radical Right makes a strong case for the importance of party leaders and activists as masters of their own fate.