Driven by the emergence of pervasive computing and the increasing need for self-managed systems, many approaches have been proposed for building software that can dynamically adapt to its environment. These adaptations involve not only changes in program flow, but also run-time recomposition of the software itself. We discuss the supporting technologies that enable dynamic recomposition and classify different approaches according to how, when and where recomposition occurs. We also highlight key challenges that need to be addressed to realize the full potential of run-time adaptable software. This survey is intended to be a living document, updated periodically to summarize and classify new contributions to the field. The document is maintained under the RAPIDware project web site, specifically, at http://www. cse. msu. edu/rapidware/survey.