The rise of anti-establishment sentiment among citizens is a feature of our times, often boosting outsider candidates around the globe. Recent works have examined the upsurge of populist and anti-establishment parties. Yet, fewer studies focus on anti-establishment citizens, the subject we delve into in this study with a twofold goal. First, to shed light on the different sources that breed an anti-establishment sentiment among citizens. Second, to connect those sources with electoral behavior. We propose to study these issues with a series of survey experiments fielded in Colombia and Brazil. Specifically, we will randomize messages containing three types of appeals that scholarship has deemed conducive to anti-establishment sentiments: perceptions of high levels of political corruption, anti-elitism, and lack of political efficacy. We expect this study to inform the design of a large-scale Facebook campaign around the 2022 presidential elections in Colombia and Brazil, aimed at curbing anti-establishment sentiments.