Reading frequently involves not just looking at words on a page, but also underlining, highlighting and commenting, either on the text or in a separate notebook. This combination of reading with critical thinking and learning is called active reading . To explore the premise that computation can enhance active reading we have built the XLibris™ “active reading machine.” XLibris™ uses a commercial high-resolution pen tablet display along with a paper-like user interface to support the key affordances of paper for active reading: the reader can hold a scanned image of a page in his lap and mark on it with digital ink. To go beyond paper, XXLibris™ monitors the free-form ink annotations made while reading, and uses these to organize and to search for information. Readers can review, sort and filter clippings of their annotated text in a “Reader’s Notebook.” XLibris™ also searches for material related to the annotated text, and displays links to similar documents unobtrusively in the margin. XLibris™ demonstrates that computers can help active readers organize and find information while retaining many of the advantages of reading on paper.