In recent electoral contests, political observers and media outlets increasingly report on the level of "authenticity" of political candidates. However, even though this term has become commonplace in political commentary, it has received little attention in empirical electoral research. In this study, we identify the characteristics that we argue make a politician "authentic". After theoretically discussing the different dimensions of this trait, we propose a survey battery aimed at measuring perceptions of the authenticity of political candidates. Testing our measure using data sets from different countries, we show that the answers to our items load on one latent concept that we call "authenticity". Furthermore, perceptions of candidate authenticity correlate strongly with evaluations of political parties and leaders, and with vote intention, while they are empirically distinguishable from other traits. We conclude that candidate authenticity is an important trait that should be taken into account by future research.