Perhaps the most common theme running through the different case-study chapters in this book is a point on which much of the research literature on clusters and cluster-related phenomena can agree: the diversity of clusters and policy responses to their development needs. In the enthusiasm for what can be broadly termed 'the cluster approach' – encouraged by the ease with which the concepts elaborated by Porter and others have fitted into existing spatial and industrial policy trends – a wide variety projects, instruments and policy strategies have been bundled together under an over-arching conceptual framework. As the chapters by Ache and myself should demonstrate, attempts to draw up single, coherent and well-defined frameworks for both cluster theory and cluster policy can only be creaky at best.