Microscopic plastic debris, so-called microplastics (MP), pose a global challenge. As most plastic is produced and used inland, the considerable lack of knowledge on their sources and impacts in freshwater ecosystems inhibits effective mitigation measures. To meet this challenge, LimnoPlast will for the first time bring together environmental, technical, and social sciences with the vision to transform a new understanding of freshwater MP to innovative solutions. LimnoPlast will: - Train a new type of scientists able to tackle the complex plastics issue holistically and contribute to Europe’s innovation and Circular Economy capacity. Working at the interface of three usually very distant disciplines, they will promote a step change in how we deal with this and future environmental challenges. - Provide the first comprehensive assessment of the sources and impacts of freshwater MP based on the analysis of three major urban areas as hotspots of plastic pollution. - Innovate technological solutions to the plastics issue, including novel processes to remove MP from municipal and industrial wastewater as well as bio-degradable, environmentally sound polymers. - Promote societal change by understanding the economic, legislative and social context of freshwater MP. - Transform science into a set of specific solutions, including (I) the prioritization of actions based on the sources and impacts of MP, development of (II) better processes and polymers, (III) risk communication strategies and societal interventions, (IV) effective policy and legislative interventions. - Transfer the LimnoPlast outcomes to European decision makers, stakeholders and the public to enable and promote action on freshwater MP using an innovative communication and dissemination strategy.