The Laurentian Great Lakes are one of the most highly invaded freshwater ecosystems in the world. Non-native species have been introduced through a variety of vectors, including ballast water, and the bait, live food, aquarium and watergarden trades. Substantial federal and international efforts have been put towards reducing the introduction of species through ballast water. In contrast, the trades in live organisms are growing in overall size and the number of species that they import. Because non-native species in these trades support commerce there is reason to allow the species if they are unlikely to become invasive. At the same time, preventing the introduction of species likely to become harmful is the best way to reduce the overall impacts of invasive species. This has led to the development and application of risk assessment tools across the Great Lakes Basin. These tools take the history of invasions and search for common traits among species that have become invasive. The assumption is that traits that have been strongly associated with invasion in the past can be used to predict which species are likely to become invasive in the future. Local, state/provincial, and federal jurisdictions across the region have independently developed risk assessment tools. These range from expert opinion to machine learning algorithms, and it is not surprising that individual species can be assessed as having very different risks depending on the tools used. Many species are now banned from import in some jurisdictions but allowed in others. The large number of risk assessment tools in use, and the long period over which they have been developed, makes the Great Lakes a particularly good case-study to investigate the promise and pitfalls of efforts to prevent new invasions in freshwater ecosystems. There are few regions in the world where so many jurisdictions are working to address invasive species in the same ecosystem. I will review the development of risk assessment tools in the Great Lakes, how and why different approaches have become popular, and how progress can be made to ensure that high risk species are prevented from introduction across the region.