The concept of virtue is a vital one for many current debates within philosophy. In particular, both virtue ethics and virtue epistemology have come to be viewed as legitimate contenders within their respective domains. The task of virtue theory – of giving an account of the virtues – is therefore an especially pressing one. If we do not have a satisfactory account of the virtues, then we will be unable to evaluate those virtue-centric approaches that have come to be accepted as legitimate contenders within both ethics and epistemology. This thesis focuses on the moral virtues and addresses two related issues. The first issue to be addressed concerns the nature of the moral virtues (or what the virtues are). I discuss three different positions on this issue: the skills model (on which a virtue is a type of skill); the composite model (on which a virtue is a combination of skill plus a characteristic motivation); and the motivations model (on which a virtue is a particular type of motivation). A chapter is devoted to each of these three models, explaining the reasons in favour of endorsing each account before then considering objections. I provide support for the motivations model by first arguing against both the skills and composite models (in Chapters One and Two). I then defend the motivations model against serious objections (in Chapters Three and Four). My aim is to demonstrate that the motivations model is a legitimate contender in this debate, and a live option for those working in virtue theory. The second issue to be addressed concerns the identity of the moral virtues (or which traits ought to be included on a list of moral virtues). I evaluate (in Chapter Five) three different approaches to identifying the moral virtues, before suggesting that we ought to consider a view whereby kindness and justice are taken to be fundamentally virtuous traits. I then (in Chapter Six) explain and defend this suggestion, by proposing a cardinal understanding of the moral virtues. I argue that this understanding is able to provide plausible accounts of specific virtuous traits, in addition to providing solutions to problems currently facing all virtue theorists. There is good reason to accept a cardinal understanding of virtue that identifies kindness and justice as the fundamental moral virtues.