This paper explores the driving forces for divergent trajectories of cluster evolution within the same branch of industry using the example of two packaging machinery clusters located in the German regions of Schwaebisch-Hall and Mittelhessen. Between 1998 and 2010 the Schwaebisch-Hall cluster recorded an increase in employment of almost two thirds. On the other hand, employment in the Mittelhessen cluster declined by about 15% and the cluster is characterised by negative functional and cognitive lock-in. This study tackles the existing lack of comparative in-depth longitudinal case studies with regard to cluster evolution. In doing so, the driving forces from recent conceptual approaches to cluster dynamics are exemplified empirically, which has rarely been done before. It is pointed out that dynamics at individual firm level (e.g. routines, spin-offs) are equally important – albeit highly interdependent – as those dynamics of relations (e.g. learning, rivalry, policy) and those operating at a systemic level (e.g. cluster heterogeneity, markets). Therefore we consider conceptual approaches to cluster evolution, which combine several driving forces to really understand changes, as necessary.