Over recent decades, clusters like industrial districts have increasingly attracted attention in economic debate. The study of clusters, particularly in the Italian literature, highlights the inadequacy of the mainstream body of explanation to provide a theory of the emergence and transformation over time of these clusters. Evolutionary theory seems to provide an adequate framework for the study of clusters. The paper applies an evolutionary perspective to the study of clusters by analysing an empirical case-study on the accordion cluster of Marche (Italy). The study of development of this cluster as an evolutionary self-organizing process will be proposed. The main concern of the paper is to highlight how the cluster analysed undertook the structural transformation which led its production from a very traditional style of manufacture to a technologically intensive one. The focus will be on the degree of continuity and complementarity between the capabilities, skills and knowledge accumulated or the trajectory exploited within the cluster over time and the new trajectory explored. By doing so, the paper analyses a particular transformation phase of the cluster under observation, that is the phase which led the cluster to a transformation in the composition of its production activity. Across this phase the paper identifies some key actors whose presence affected the possibility for the cluster to undertake the transformation. The relevance of these actors is related to their role within the internal production chain as well as to their external networking.