Leadership research so far has neglected regional clusters as a particular context, while research on networks and clusters has hardly studied leadership issues. This paper fills this dual gap in the abundant research on leadership on the one hand and on networks/clusters on the other by investigating leadership in four prominent photonics clusters in England, Scotland, Germany and the United States. Apart from giving an insight into the variety and patterns of leadership practices observed in these clusters, the paper addresses the dilemma that regional innovation systems such as clusters usually have a critical need of some kind of leadership, but that neither individual nor organizational actors wish to be led. This dilemma or paradox can only be 'managed' by organizing for leading (in) clusters in a way that takes into account the tensions and contradictions surrounding leadership of and in clusters. The argument is based upon the idea of leading as reflexive structuration that has far-reaching implications for leadership research not only in this and other macro contexts but also in more traditional contexts.

Much research on regional business clusters refers to path dependence as a central feature in the evolution of cluster structures. In many cases, however, little is known about the agentic processes and mechanisms that underlie path dependence. In this article, we explore changes in a specific network in the optics cluster in the German region of Berlin-Brandenburg to show that development of clusters can be driven by elements of both emergence and planning. In particular, we argue that current actors actively and purposively draw upon rules and resources that were shaped not only in the long and discontinuous history of the cluster but also in the recent process of network development that involves careful planning and well-structured planning tools. Using central concepts from structuration theory, we show how agency is implicated in the coordination of the network and how agency turns coordination into a self-reinforcing mechanism. The findings suggest that purposive planning involves a fundamental ambivalence in the processes and outcomes of path dependence, at the level of both the cluster and its constituent networks. Copyright (c) 2010 Clark University.

In this article we consider the nature and implications of barriers to collaborative process learning that may occur in regional clusters. Our approach is rooted in research in interorganizational collaboration and focuses on interview-based research in photonics clusters in: Scotland and the West Midlands in the United Kingdom; Berlin-Brandenburg in Germany; and Arizona in the United States of America. From this research we develop characterizations of the barriers to collaborative process learning in clusters at three levels of analysis-the macro, micro and meso levels. We also develop an integrated conceptualization of these barriers, which reveals a difficult tension between 'authority' and 'anomie'. This tension has implications for the management of process learning, but also connects with recent debate about whether learning is most helpfully understood as an individual or collective process.

This paper aims to further our emerging knowledge on the external linkages of clusters. We adopt a network governance perspective and study connected clusters as goal-directed, multilevel whole networks that we denote as 'cluster networks'. Based on an analysis of four empirical cases varying in regional scope, age, and industry context, we identify two governance forms: internally governed cluster networks are formed to establish ties among cluster representative organizations to share knowledge and pool resources on selected activities; externally governed cluster networks are formed to systematically develop crosscluster ties and competences on and across levels and are brokered by a central inter-cluster administrative organization and several decentralized lead organizations. Our findings show that cluster connectivity can go beyond organization-based pipelines and personal relationships to include clusters as governed entities, albeit with different intensities regarding the brokerage of ties on lower levels.