Practical reasoning is necessary for human survival and flourishing, and it is the condition that makes possible the economic, social, political and legal activities. It is assumed that practical wisdom exemplifies the best form of practical reasoning. But what is practical wisdom? What does a practically wise person know? It is widely held that a person is practically wise if and only if the person knows how to live well, and that a person knows how to live well only if the person knows what is good or important for well-being. The question is: What is it that contributes to or constitutes well-being known by a wise person? A theory of wisdom without a substantive answer to this question can never be seriously tested and used in practice. In this paper, I propose a fully articulated theory of wisdom by integrating the skill theory of wisdom with the success theory of well-being, arguing that practical wisdom is a skill conducive to well-being conceived as attitude success.