This article explores the Europeanization of Czech politics in the pre-accession period, with a principal focus on the political parties and party system. It argues that Czech political parties and party politics became increasingly Europeanized with the increased integration of the Czech Republic into the EU. In turn, the parties have played a key role in the Europeanization of Czech politics. This role is evident in the outcome of the June 2003 referendum on EU membership, which reflected strong cross-party support for EU accession (excepting the Communists). However, factors other than party support also influenced voters' choices, including regional factors and socio-economic factors such as employment status and level of income and education. Copyright 2006 Blackwell Publishing Ltd.