Adaptability can be defined as the ability of a system to fit to changed circumstances. Adaptability is a property related to engineering as well as to the execution of networked service systems. This paper considers general issues of adaptation at two abstraction levels: 1) System of entities, terrain, functions and adaptability types, and 2) Architectures supporting adaptability. Adaptability types defined are capability-related, functionality-related and context-related adaptation.Architecture is constituted by computing architecture and service management architectures. The computing architecture specifies service systems by a combination of Extended Finite State Machine, goals and policies. The service management architecture defines functionality components that realize the various adaptability types