The development of machine or computer applications for the arrangement, storage, retrieval, and display of literature references or classification schedules, vocabularies, and indexes used with the Universal Decimal Classification (UDC) System as an access point is reviewed. Activities of the Subcommittee on Mechanization of the UDC Central Classification Commission of the International Federation for Documentation are described and international conferences on "UDC in Mechanized Retrieval Systems" are summarized. More than 60 existing operating systems in 15 countries are described and samples of their output are provided. A bibliography on mechanization and the UDC is included. (Author/DGC)