In this paper, I take up one of Wang Yangming’s most audacious philosophical claims, which is that an achievement that is entirely concerned with correcting one’s own inner states, called “establishing sincerity” (licheng 立誠), can help one to fully grasp all ethically pertinent matters. I begin with a reconstruction of what Wang means by “establishing sincerity” and then turn to two sets of controversies regarding his audacious claim. The first has to do with how we should understand the proposal that establishing sincerity positions a person to fully grasp all ethically significant concerns, and to what extent it makes room for investigation of external facts. The second has to do with whether we can preserve Wang’s core account of virtuous moral agency without his strong ethical nativism, according to which we achieve virtuous outcomes by relying primarily on well-formed inborn capacities rather than acquired knowledge. I consider some arguments and interpretations of Wang’s thought that might allow us to bypass his “implausibly” nativist presuppositions, and conclude that they do not succeed. Even if we cannot accept his strong ethical nativism, however, there is a range of important ethical norms for which Wang’s prescriptions are powerful and prudent.