Salts naturally occur in most fresh waters. However, human activities such as agriculture, resource mining, the application of road deicing salts, and climate change are increasing the concentration of salts in fresh waters around the world. All types of freshwater environments have been affected by salinization, including those that are used for drinking water and recreation. Since most freshwater organisms do not have a recent evolutionary history with high salinity, it is essential that we identify the impacts of salinization. This session features the latest research on the ecological and evolutionary impacts of freshwater salinization, and how those impacts might affect society by reducing the quality of services provided by fresh waters. Leading researchers in this field will describe how rising salinity in fresh waters can substantially alter community structure and function through direct or indirect effects. They will also demonstrate that the impacts of salinization differ among regions, and across abiotic conditions. Furthermore, the source of salinization determines the types of ions associated with salinization, which can determine the magnitude of effects on freshwater environments. Other speakers will describe how salinization triggers evolutionary responses in freshwater organisms. We will also highlight how evolutionary responses can instill ecological communities with increased stability, but other responses can be maladaptive. This goal of this session is to integrate contemporary research on freshwater salinization and provide future research directions with implications for policy and management.