This paper provides an overview of the concepts and design of the Adaptive Multimedia Information System (AMIS). AMIS is a software application for the playback of natively accessible content (DAISY and DAISY/NISO books), and of accessibly authored HTML pages. DAISY playback includes support for SMIL elements and the Navigation Control Center. AMIS retrofits HTML documents with a navigation overlay that enables accessible presentation through synthesized speech, large print, and Braille renderings. AMIS employs a flexible XML-based architecture that allows for adaptation of the standard interface to meet the needs of both users and assistive technologies. The mutable application interface allows it to adapt to user preference, content delivery mode, and assistive device capabilities. Users may customize font size, color contrast, spacing, volume, playback speed, and presence/absence of interface regions. Core interface features are derived from both the DAISY playback model and the W3C User Agent Accessibility Guidelines. AMIS XML documents describe application components (controls, content layout regions, dialogs, content renderings) aurally, textually, and visually. The default application interface allows for visual and aural output; and touchscreen, mouse, and keyboard input. Through the use of the AMIS Plug-in SDK, developers can write interfaces to a variety of assistive devices. These devices can gain access to the same application functionality and content as does the native interface. Localization is also very easily obtainable in AMIS, because every aspect of the interface is customizable. Labels on buttons and regions are all imported directly from the system’s Interface Markup documents. The plug-in architecture allows for the addition of new input methods, to accommodate techniques such as IME (Input Method Editor generally used for East Asian languages) and on-screen keyboards. The adaptable interface framework and the content rendering capabilities, coupled with the use of open standards, enables the customization or addition of features to meet a broad range of user requirements.