Reciprocity as one of the basic principles of human being is still a neglected concept in political science that remains elusive. It refers to an individuals' in-kind response to friendly or hostile acts. Previous research from other disciplines has shown that reciprocity generates positive externalities and implies the maintenance of stable social societies. For example, it fosters the probability of an individual’s political participation. Gutman and Thompson (1996) even promote the principle of reciprocity as the basis of deliberative democracy. Under reciprocity, individuals use deliberation with the goal of reaching deliberative agreement that, in turn, supports a political process fostering moral learning. However, it is difficult to measure and previous research rather refers to trust and trustworthiness. By survey experiments, this study measures reciprocity in a comparable way to analyze in a second step the relationship between the principle and the quality of democracy. First results will be presented.