Elizabeth Mendenhall article lays out “A research agenda to propel policy development” regarding ocean plastics. According to Mendenhall, although the phenomenon of marine plastic debris is now widely recognized as a problem for the international community, significant gaps in understanding still inhibit the creation and implementation of effective policy responses. This paper reviews the state of scientific knowledge about the causes and consequences of marine plastic debris, including its sources, pathways, composition, location, and impacts on ecosystems and human activities. Much remains unknown about the large scale impacts of plastic debris on ecosystem functions and human health, among other information gaps. Mendenhall suggests that additional scientific research about the nature, extent, and harms of marine plastic debris could increase the political salience of the problem, and produce urgent and focused attention on the formulation of solutions. She also notes that while many policy responses have been proposed, and even pursued, additional research could assist in the prioritization of the most cost-effective strategies. Finally, Mendenhall offers that the research agenda outlined would support a more detailed and comprehensive assessment of the nature of the problem of marine plastic debris, and inform the creation and implementation of effective solutions.