The papers in this volume were presented at the Second Annual Work­ shop on Active Middleware Services and were selected for inclusion here by the Editors. The AMS workshop was organized with support from both the National Science Foundation and the CAT center at the Uni­ versity of Arizona, and was held in Pittsburgh, Pennsylvania, on August 1, 2000, in conjunction with the 9th IEEE International Symposium on High Performance Distributed Computing (HPDC-9). The explosive growth of Internet-based applications and the prolifer­ ation of networking technologies has been transforming most areas of computer science and engineering as well as computational science and commercial application areas. This opens an outstanding opportunity to explore new, Internet-oriented software technologies that will open new research and application opportunities not only for the multimedia and commercial world, but also for the scientific and high-performance computing applications community. Two emerging technologies - agents and active networks - allow increased programmability to enable bring­ ing new services to Internet based applications. The AMS workshop presented research results and working papers in the areas of active net­ works, mobile and intelligent agents, software tools for high performance distributed computing, network operating systems, and application pro­ gramming models and environments. The success of an endeavor such as this depends on the contributions of many individuals. We would like to thank Dr. Frederica Darema and the NSF for sponsoring the workshop.