Members of the WTO are negotiating new rules on fisheries subsidies with the aim of concluding a multilateral agreement on this issue by the end of 2020. However, there is currently very little guidance available about the reform of fisheries subsidies, either in the context of a possible WTO agreement or to guide unilateral reform. This policy brief sets out some early thinking about the possible implementation of new WTO subsidy rules. It starts by presenting general implementation steps WTO members could take to fulfill their obligations for subsidy reform under agreed disciplines, irrespective of any specific rules. It then describes some of the more concrete steps that might be required to implement particular disciplines in the three main substantive areas under discussion at the WTO—i.e., subsidies that contribute to (1) illegal, unreported, and unregulated fishing, (2) the fishing of overfished stocks, and (3) overcapacity and overfishing more broadly. Finally, the brief shortly discusses the role of technical assistance in helping developing WTO members to successfully reform their fisheries subsidies, including through a potential change in the focus of existing assistance programs.