Eighty-three percent of respondents to a Center for Digital Government survey report being concerned about security of data stored in the cloud. This isn’t a big surprise. Much of government data is related to security issues or personally identifiable con¬stituent and employee information. And government IT staff must guarantee that applications, data, and departments or agencies are securely isolated in spite of residing in multi-tenant environments. This issue brief explores the security issues surrounding these increasingly popular multi-tenant environments. It introduces storage architecture strategies to ensure the secure separation of tenant data, and provides tips for evaluating enterprise cloud architectures.