This chapter starts by clarifying the comparative framework and the primary sources of survey data employed in this study. The book is based upon the ‘most different’ research design, including thirty-nine countries with contrasting democratic histories, patterns of industrial development, and political institutions, as well as divergent electoral fortunes for the radical right. Countries are compared if included in either of the primary survey data sources: the European Social Survey 2002 and the Comparative Study of Electoral Systems 1996–2001. The national variations are important since they provide insights into the underlying conditions facilitating electoral support for these parties. The chapter then discusses the best way to conceptualize and define parties such as the French Front National, the Austrian FPÖ, and the Belgian Vlaams Blok, and explains the party typology used in this study. For a consistent classification, this book uses both ‘expert’ and ‘voter’ judgments to identify the location of parties across the ideological spectrum. This chapter draws upon the most recent expert survey, conducted in 2000 by Marcel Lubbers, supplemented by those contained in the Comparative Study of Electoral Systems and by similar sources. Careful classification is an important preliminary step before examining whether parties within the radical right family share certain similar social and ideological characteristics, as so often assumed. On this basis, Chapter 3 then goes on to briefly summarize the electoral fortunes of the most significant contemporary radical right parties studied in depth throughout the rest of the book.