Of the four cardinal virtues of the Platonic and Thomistic traditions (wisdom, justice, courage, and moderation), only one corresponds, even approximately, to any of the four cardinal Mencian virtues (benevolence, righteousness, propriety, and wisdom). Consequently, philosophers who study virtue should find Mencius a rich resource. Unfortunately, there are not many detailed published studies of the Mencian virtues. In this paper, I want to examine in some depth Mencius' understanding of the virtue of yi, conventionally translated as “righteousness.” In Section I, I lay the background for my discussion of righteousness by outlining the Mencian view of self-cultivation and the virtues as a whole. In Section II, I examine how the virtue of righteousness is related to the key Mencian notion of “extension.” In Section III, I discuss the relationship between righteousness and shame. Finally, in Section IV, I briefly discuss some of the philosophical problems raised by Mencian righteousness.