: The software industry is faced with the fast growing complexity of IT infrastructures. This makes manual administration increasingly difficult and appears to be the limiting factor in the general development of such infrastructures. This complexity crisis has stimulated many researchers to propose software systems that are allegedly self-organizing. However, often, this claim is only based on vague intuitions about selforganization, and a proper classification is missing. From a scientific standpoint, this is questionable and undesirable since it adds confusion rather than clarity. In this article, a framework is proposed that enables researchers to classify their systems and to state clearly, verifiably, and reproducibly why and in which way they are self-organizing. This framework provides a definition of the properties of a self-organizing system, it defines a respective class of systems denoted as SO, and it offers a methodology for proving that a given system is belonging to SO ...