In this thesis I argue that emotion is integral to practical rationality, contrary to the dominant tradition that has held that emotions are irrational and dangerous disruptive influences that we'd be better off without. In Chapter 1 I argue that practical rationality consists in doing what one has most normative reason to do, and in Chapter 2 that an agent is practically rational to the extent that she responds to her reasons; this is how she guides her actions in line with the norm of doing what she has most reason to do. This can be done in ways other than by the employment of practical reasoning. In Chapter 3 I argue for a picture of practical reasoning that stands against the division of emotion and rationality. This account makes room for the overwhelming evidence that challenges the traditional view of emotions as the enemy of practical rationality. Chapter 4 gives a brief overview of the philosophical literature of emotions, and their place in practical rationality. In Chapter 5 I argue that emotions provide us with the necessary access to our reasons for action which we need in order to be able to respond to them, and thereby to be practically rational. Further, as I argue in Chapter 6, emotions play vital roles in the process of practical reasoning itself. Thus practical rationality would not be better off without emotion. In Chapter 7 I argue that we should distinguish between two types of incontinent action (acting against ones all things considered judgement about what one has most reason to do) and that one of these - weakness of will - is necessarily irrational, but the other - akrasia - is not. In Chapter 8 I apply my thesis to the question in the practical domain of what it means to 'lose self-control' in the context of killing in response to a provocation, which is a defence to murder. I argue that the 'control' that is lost is the regulative guiding control characteristic of the reason-responder. Understanding practical agency as reason-responsiveness, and understanding the role that emotions play within it as per my thesis, enables this coherent understanding. Thus I am arguing for neither a pro-emotion nor anti-emotion view of the role of emotion in practical rationality. Emotions should not be seen as either 'for' rationality nor 'against' rationality: they are simply part of rationality.