One of the most controversial issues in applied ethics today concerns the morality of enhancement. Psychopharmaceuticals that enhance memory, concentration and promote self-confidence are already available and there is anecdotal evidence that they are widely used. The issues raised by these drugs are pressing. However, we should not allow these drugs to distract us from other, apparently more innocuous, ways of enhancing ourselves, by altering the environment in which we live and act. The aim of this project is to investigate the relative efficacy of psychopharmaceutical means of enhancing free will compared to environmental manipulations. We will focus on a central component of free agency: self-control. There is already an extensive literature examining how self-control can be undermined by subjecting individuals to tasks that exhaust it. There is also a growing literature on how these effects can be mitigated. But most of these methods leave the agent in a worse state than before: though in the short term they allow for the exercise of self-control, in the long run they undermine it. We will test whether pharmaceutical means of mitigating self-control depletion are subject to the same limitations. We also aim to contribute to the closer integration of neuroscience and social psychology by gathering evidence that will shed light on the question whether neuroscientific measures of executive control tap into the same capacities as psychological measures of self-control. We will integrate the data gathered into a scientifically informed account of free will and moral responsibility. Finally, we will assess the implications of the scientific and conceptual work carried out here for law and social policy.