The trend towards powerful workstations and high-speed networks has enabled applications to communicate and manipulate digital audio and video. These are continuous media and differ from discrete media such as text and graphics in that they have stringent delay and bandwidth requirements. Neither the mechanisms used to transport ordinary data over networks nor present communication protocols are sufficient to communicate continuous media. Special operating system support must also be provided to meet the requirements of both discrete and continuous media in future multimedia applications. This volume contains the proceedings of the Second International Workshop on Network and Operating System Support for Digital Audio and Video, held in co-operation with ACM SIGCOMM and SIGOPS at the IBM European Networking Center in Heidelberg, Germany, in November 1991. The volume contains 33 selected papers together with summaries of the workshop sessions compiled by the session chairmen.