ESR13 will investigate risk perceptions and mental models regarding freshwater MP, comparing citizens and experts. Mental models are a set of causal beliefs that allow people to anticipate future consequences, guide perceptions of risks and benefits and ascribe responsibility and behavioural choices. ESR13 will analyse people’s mental models and perceptions of the sources of freshwater MP, pathways, associated risks, and benefits as well as of behavioural components and alternatives. ESR13 will start out with qualitative analyses to explore people’s views on MP, studying perceived sources and routes of MP into freshwater systems and perceived impacts on both ecosystems and humans. Public perceptions will be contrasted with expert views provided by LimnoPlast collaborators. The survey instruments will tap into people’s intuitive, affective, and vague conceptions of MPs as well as into more elaborate models and ascriptions of risks and benefits. In close cooperation with ESR14, the roles of consumers and industry in people’s mental models will be investigated to identify which factors shape acceptance of solutions and support for ameliorative policies.