This monograph is intended to provide a snapshot of the status and opportunities for advan- cement in the technologies of dynamics and control oflarge flexible spacecraft structures. It is a reflection ofthe serious dialog and assessments going on all over the world, across a wide variety of scientific and technical disciplines, as we contemplate the next major milestone in mankind’s romance with space: the transition from exploration and experimentation to commercial and defense exploitation. This exploitation is already in full swing in the space communications area. Both military and civilian objectives are being pursued with increasingly more sophisticated systems such as large antenna reflectors with active shape control. Both the NATO and Warsaw pact alliances are pursuing permanent space stations in orbit: large structural systems whose development calls for in-situ fabrication and/or assembly and whose operation will demand innovations in controls technology. The last ten years have witnessed a fairly brisk research activity in the dynamics and control oflarge space structures in orderto establish a technology base forthe development of advanced spacecraft systems envisioned for the future. They have spanned a wide spectrum of activity from fundamental methods development to systems concept studies and laboratory experimentation and demonstrations. Some flight experiments have also been conducted for various purposes such as the characterization of the space enviroment, durability of materials and devices in that environment, assembly and repair operations, and the dynamic behavior of flexible structures. It is this last area that has prompted this monogram.