Illegal markets differ from legal markets in many respects. Although illegal markets have economic significance and are of theoretical importance, they have been largely ignored by economic sociology. In this article we propose a categorization for illegal markets and highlight reasons why certain markets are outlawed. We perform a comprehensive review of the literature to characterize illegal markets along the three coordination problems of value creation, competition, and cooperation. The article concludes by appealing to economic sociology to strengthen research on illegal markets and by suggesting areas for future empirical research.