Students with disabilities and special needs have faced challenges in accessing educational content, and in taking traditional pen-and-paper tests. How might technology improve the process, while making statewide tests truly accessible to all students? NimbleTools is the first computer-based test delivery system that incorporates principles of universal design by building in multiple accessibility tools designed to meet various needs of students. The program flexibly adjusts the accessibility tools available to students; students select when and how to use each tool while performing a given test item. Its success in two pilot studies suggests that computer-based test delivery can improve students' access to tests and their ability to demonstrate knowledge. The development of NimbleTools illustrates how the principle of universal design can be applied to ensure that all students have access to the tools they need to demonstrate what they actually know and can do. (Contains 3 figures and 3 tables.)