Aristotle argues that the actions central to human flourishing are those that involve reason. But reason manifests itself in a human life in more than one way. We employ reason to investigate what there is (theoretical reason) and when we determine what to do (practical reason). Aristotle's elucidation of practical reason involves the introduction of a distinctive practical way of being true; however, practical truth--which he describes as truth in agreement with right desire--is notoriously difficult to understand. The sixteen essays in this collection concern both the history of practical truth throughout the intervening centuries and the role it currently plays in contemporary ethics and action theory. While there is no consensus in this volume about how we should understand the details of practical truth, there is a strong consensus that this concept will be valuable to those who are sympathetic to the idea that living well for a human being necessarily involves a specifically practical form of knowledge and wisdom. Practical truth has the potential to help us mark the difference between knowing the good and doing the good--a difference we are all know well.