The paper reconstructs the classical Confucian approach to sincerity (cheng 誠) as a political virtue of the governing and a civic virtue of the governed. For Confucian thinkers, sincerity thus understood shapes both the rulers and the ruled in terms of the common good, and guarantees the stability of a just political system. It is shown that for Confucius and the Zuo Commentary one of the key political and civic virtues was reliability (trustworthiness, xin), which later came to be viewed (...) as rooted in an inner virtue of sincerity, described by Mencius as natural, inherently moral, and social. The relation between moral and civic/political sincerity was then examined in the Great Learning and the philosophy of Xunzi. Their ideas were complemented in the later imperial period in the Essentials of Governance with a discussion of the connection between political sincerity and the virtue of loyalty (zhong). (shrink)