As Steenbergen and Marks (Introduction) describe, scholars of EU policy-making have adopted conflicting assumptions about the dimensionality and character of the EU policy space. Since the shape of the political space – the number of dimensions, the policy content of these dimensions, and the location of actors in this space – is a central determinant of political competition and outcomes, these conflicting assumptions often lead to different conclusions about and interpretations of EU policy-making. This is a serious impediment to advancing our theoretical understanding of EU politics. A resolution of this theoretical conflict depends on assessing the relative value of the conflicting assumptions about the character of the policy space.

To help address this problem, we attempt to examine empirically whether the structure of the EU political space is consistent with these existing models. Specifically, we investigate whether the existing models described by Marks and Steenbergen (in this book) account for the EU policy space as defined by the European party federations – or “Euro-parties.” These Euro-parties bring together the domestic and European-level political elites in the four main European party families – socialists, Christian democrats/conservatives, liberals, and greens. In the European elections of 1979, 1984, 1989, 1994, and 1999, the Euro-parties drafted manifestos describing their positions across a broad range of policies involving the EU. We use an established content analysis technique to turn these text documents into numerical data representing Euro-parties' positions on specific political issues.