Voting Advice Applications (VAAs) have experienced a great deal of success over the past decade, and are now used in many countries around the world. This editorial introduces a Special Issue resulting from a section of the 2015 European Consortium for Political Research (ECPR) conference in Montreal, organized by the ECPR's official VAA Research Network. It discusses the global spread and the popularity of these tools, addresses the history and different branches of VAA research, the current state of the art, and the remaining puzzles in the field. It also focuses attention on the wealth of research that is examining the effects of VAAs on political parties, candidates, and voters, as well as how VAA design choices affect the advice given to voters and their subsequent voting behavior. We hope this Special Issue will also highlight the potential of VAA-generated data for studying party positioning over time and across countries, allowing for comparative analyses of the characteristics and development of parties and party systems.KEY WORDS: Voting Advice Applications, VAA, voting, democracy, voting behavior Voting Advice Applications (VAAs) have experienced a great deal of success over the past decade. They are now used in many countries around the world, and previously isolated VAA research efforts and projects have recently been pooled in an effort to establish a research community focusing on the idea, design, and implications of these tools. This Special Issue of Policy & Internet gathers together articles first presented at a section of the 2015 European Consortium for Political Research (ECPR) conference in Montreal, 1 organized by the ECPR's official VAA Research Network. By bringing together these articles we hope this Special Issue will help focus attention on the wealth of research that is examining the effects of VAAs on parties, candidates, and voters, and how VAA design choices affect the voter advice given and subsequent voter behavior. We also hope the issue will highlight the potential in VAA-generated data for studying party positioning over time and across countries, allowing for comparative analyses of the characteristics and development of parties and party systems.