This book analyses how people decided to participate in and who to vote for over the course of the 2009 and 2013 German federal election campaigns. Using data from two seven-wave campaign panel surveys collected in the framework of the German Longitudinal Election Study (GLES), it demonstrates that both turnout and vote choice, as well as their attitudinal precursors, underwent considerable individual-level changes in the run-up to these elections. Fixed-effects panel regression analyses show that campaign efforts, controversies and events did influence voting behaviour. These effects were not confined to certain subsections of the electorate, either in terms of political involvement or partisanship. Campaign effects led some party adherents back to the fold, whereas they made others defect. In the German multiparty system, campaigns are capable of making a difference to voting behaviour. This analysis thus casts doubt on the general applicability of the minimal effects model.