Much of what makes documents accessible to people with disabilities and their assistive technologies boils down to the file format. Every format comes with benefits and drawbacks when it comes to accessibility. Which format or formats should libraries choose to best benefit their patrons and the needs of archives and discovery? This talk will cover the vagaries of different formats, including providing insights to popular formats such as Markdown (avoid!) and the potential of the relatively new accessibility features in EPUB3 that may one day permit moving away from PDFs.