Abstract : This Final Report summarizes the results of a research effort directed towards the development of adaptive decentralized control systems. The adaptive controller in such a system must operate in the presence of unmodeled dynamics. An input-output approach was developed for analyzing the global stability and robustness properties of adaptive controllers under such circumstances. Conditions for guaranteeing global stability of the error system associated with the adaptive controller, and ensuring boundedness of the adaptive gains, were derived. Contents: Lattice Implementation of Some Recursive Parameter Estimation Algorithms; And Efficient Technique for Output Error Model Reduction; An Output Error Method for Design of Reduced Order Controllers; Robust Adaptive Control: Conditions for Global Stability; Decentralized Design of Decentralized Controllers.