Invasions by non-native species are changing the composition and function of many communities across the globe.  Non-native species dominate some terrestrial, wetland, freshwater, and marine ecosystems --- in terms of species richness and abundance --- and can exert strong effects as predators, competitors, parasites and pathogens of native biota.  As a result of such strong interactions, non-native species can dominate community structure, foodwebs, energy flow, and ecosystem-level processes such as primary productivity, sometimes over large spatial scales.  These impacts pose significant challenges for conservation and restoration, as non-native species can operate to undermine a desired outcome for target species or habitats.  Some invasions impose significant economic costs (through loss of agriculture, forestry, and fisheries products), and others have severe human health effects, including mosquito-borne viruses and toxic algal blooms.  While it is clear that invasions have myriad ecological and social impacts, based on detailed analyses for several high-profile species in various ecosystems, these serve primarily to highlight the types and potential magnitude of invasion impacts that exist, but the effect of most non-native species and the full scope of impacts from invasions remains poorly resolved.  To address this gap, SERC research uses a variety of observational, experimental and modeling approaches to characterize and test the ecological, evolutionary, and social effects of non-native species across diverse ecosystems.  This work advances understanding of how the Earth’s ecosystems function and also serve to inform resource management and conservation strategies.