The reuse of software has been an eagerly sought yet elusive goal of software developers for decades. Many promising technical approaches have been pursued, but none have yielded the full potential. Recent advances in software technology R&D have led to substantial progress in the pursuit of software reusability. One of the more promising avenues of work is compositionbased (component-based) software construction. This paper explores the compositional approach to the construction of software in general and presents a 'technology roadmap' for software composition. This roadmap depicts the interdependencies and state of the technologies necessaiy to fully realize software composition.