Accessible instructional materials are materials which can be used by students with disabilities as easily, effectively, and thoroughly as students without disabilities. Unfortunately, policy evidence suggests the California Community Colleges are not ensuring instructional materials are accessible. Surprisingly, while accessibility is often discussed as an equity issue, little evidence links accessible instructional materials to disabled student success. Additionally, there is no existing instrument which measures disabled students' perceptions of accessibility. The purpose of this quantitative pilot study was to (1) develop an instrument to measure disabled students' perceptions of the accessibility of their instructional materials, and (2) determine whether there is a relationship between perceived accessibility and perceived learning. The influence of disability type, use of accommodations, and attitudes towards requesting accommodations on perceived learning were also investigated. In this study, items for the Perceived Accessibility of Instructional Materials (PAIM) instrument were developed based on the Web Content Accessibility Guidelines (WCAG) principles of perceivable, operable, understandable, and robust materials. College students with disabilities (n = 116) completed a survey instrument containing the 33-item PAIM instrument, six items from the CAP Perceived Learning Scale, and additional items related to disability type, use of disability accommodations, attitudes towards requesting accommodations, and demographic information. Results of factor and reliability analyses indicated the four scales of the PAIM instrument are separately valid and reliable indicators of perceived accessibility. Additionally, a regression model indicated perceived accessibility was a significant predictor of perceived learning. Disability type was not a significant predictor of perceived learning and use of accommodations and attitudes towards accommodations did not significantly moderate the relationship between perceived accessibility and learning. The results suggest the initial PAIM instrument is a promising starting point for further scale development work to measure perceived accessibility. Importantly, this study also provides the first known quantitative evidence of a relationship between accessibility and disabled student learning. Recommendations include the use of the PAIM instrument by practitioners in tandem with an expanded focus on institutional accessibility leadership, faculty professional development, and policy resources. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]