What is defiance, and when does defiant behaviour impede one's ability to aim at flourishing? People who are defiant can present perplexing challenges etiologically, diagnostically, and responsively. But in order to understand accurately when defiant behaviour is good, or bad, or neither (when it emerges out of mental illness), a fresh perspective on defiance is needed. This book offers a nuanced and complex look at defiance, taking seriously issues of dysfunction while also attending to social contexts in which defiant behaviour may arise. Those living in adverse conditions such as oppression, systematic disadvantages, and disability may act defiantly for good reasons. This perspective places defiance squarely within the moral domain; thus, it should not be assumed that when professionals come across defiant behaviour, it is a sign of mental dysfunction. Potter argues that defiance sometimes is a virtue, meaning that a disposition to be ready to be defiant when the situation calls for it is part of living a life with a realistic understanding of the aim of flourishing and its limits in our everyday world. Her work also offers theoretical work on problems in knowing that can impede understanding and responsiveness to those who are, or seem to be, defiant. Clinicians, teachers, social workers, nurses, and others working in helping professions are invited to engage in different ways with defiance so as to better understand and respond to people who express that defiance. Case studies, a framework for differentiating different forms of defiance, a realistic picture of phronesis-practical reasoning-and an explanation of how to give uptake well are some of the topics covered. The voices of service users strengthen the author's claims that defiance that is grounded in phronesis is just as much a part of moral life for those living with mental disabilities as for anyone else.