In summer 1996, OCLC Forest Press published the 21st edition of the Dewey Decimal Classification (DDC 21). For the first time, a new edition of the classification was published in two formats: the traditional four-volume print format and an electronic version on CD-ROM (Dewey for Windows). The publication of Dewey for Windows completed several years of collaborative effort by OCLC and Forest Press staff. The goal was to produce an electronic version of the DDC that employs the electronic form to maximum advantage but remains sensitive to traditional features that carry over to the new media. In addition to the publication of Dewey for Windows, the collaboration between OCLC researchers and Dewey classificationists has resulted in an active classification research program. This article provides an update on the Dewey research program described by Vizine-Goetz and Mitchell  and introduces new research springing from that work.