Political polarization is one of the most debated topics in the world (Fiorina and Abrams, 2008). It shapes our political identities and the way we view a variety of aspects in life (e.g., the economy, general satisfaction with one’s nation). With the present research, we will answer the following question: "Does political engagement in the form of expressing support causally impact political beliefs?" The present research addresses the limitations of the existing literature heads on. Firstly, we overcome the identification problem by relying on evidence from a novel, carefully designed experiment. The experiment crucially focuses on two factors that induce polarization via cognitive dissonance: the exerted effort to support a political candidate and the outcome of the election. Secondly, we will recruit a representative sample of citizens from the US via the panel company Dynata to increase the generazability of the results. Moreover, we will contribute to the existing literature conceptually by building a micro-founded model of political beliefs change and polarization with cognitive dissonance theory as its basis. Finally, we will test whether the changes in beliefs, induced by cognitive dissonance, have consequences on real decision by asking participants in the experiment to contribute to charitable organizations affiliated with various political camps. The results of the present research will deliver many important implications for how we organize our societies and how we interpret polarization.