•An impact pathway framework traces the flow of plastics through the socioeconomic system.•We identify key policy entry points and associated policy instruments.•Policy instruments range from traditional market based to behavioral tools.•We produce a toolbox for policy design that is responsive to measurable indicators.•We apply the impact pathway and toolbox to make country-specific recommendations. The polluting of marine ecosystems with plastics is both a global and a local problem with potentially severe consequences for wildlife, economic activity, and human health. It is a problem that originates in countries’ inability to adequately manage the growing flow of waste. We use an impact pathway framework to trace the flow of plastics through the socio-ecological system and identify the role of specific policy instruments in achieving behavioral changes to reduce marine plastic waste. We produce a toolbox for finding a policy that is suitable for different countries. We use the impact pathway and toolbox to make country-specific recommendations that reflect the reality in each of the selected countries.