Adam Smith seeks to explain in the Wealth of Nations and Lectures on Jurisprudence the persistence of slavery as an institution. In order to accomplish this, he also draws on arguments he had developed in The Theory of Moral Sentiments. The result is a sophisticated explanation that bridges economic, psychological, and moral considerations. After presenting Smith’s explanation, I will consider a discussion of the moral wrong of slavery in the work of Ottobah Cugoano, author of the incisive criticism of the slave trade Thoughts and Sentiments on the Evil of Slavery. I will suggest that Cugoano’s account of what is morally wrong in slavery shows an important lacuna in Smith’s views.