The paper investigates the constitutional regulation of interest groups and political parties across contemporary European constitutions. It builds on an established theoretical framework (Biezen and Borz 2012) and uses the data set developed by the Party law in Modern Europe project (http://www.partylaw.leidenuniv.nl). The paper tests hypotheses in relation to the magnitude and extent of pressure group regulation with the aim of gauging similarities and differences between their constitutional regulation. It further compares the regulation of parties and interest groups as established by constitutions by taking into consideration contextual factors such as the newness of democracy, models of corporatism, levels of EU lobbying. The analysis is based on the content analysis of contemporary constitutional articles with reference to pressure groups by employing a combined qualitative and quantitative approach. The analysis will also take into consideration the constitutional amendments with relevance to parties and pressure groups and the context around their adoption. The relevance of comparing the constitutionalization of parties and pressure groups relates to the role and type of political organizations for democracy.
