This paper examines Popper's views about ethics and metaethics, drawing on a wide variety of sources. It notes the presence of Kantian and utilitarian themes, and discusses some ideas about how they might be interpreted and inter-related. It argues that there are various problems about Popper's views ― notably that his Kantian-influenced ideas about the significance of the individual conscience would appear to conflict with the emphasis on inter-subjectivity in his more general epistemology. The author suggests that it is not likely that a resolution to the issues which he raises will be found in Popper's own work, and advocates, as a research programme for critical rationalism, the adoption of a strong form of ethical realism, and argues that Popper's own treatment of reduction suggests the legitimacy of exploration of these matters in a non-reductionistic manner, prior to the attempting of reductions.