Introduction

The European 2020 Strategy has put innovation at the heart of European efforts to strengthen the competitiveness ofthe European economy. For this purpose, the creation and support of clusters at regional level has been stressed as one of the key actions to be implemented.AsshownbytheinitiativesoftheEuropeanCommissionincludingthecreation of a European Cluster Observatory, clusters are a key concern at European level. However, clusters have been an essential focus of national and region policies too. In2008theEuropeanCommission publishedaCommunication onaninnovationstrategy for the Union based on the development of world-class clusters, a "policy framework for better complementarities and synergies between the different policy levels with a view to supportingthedevelopmentofmoreworld-classclustersintheEU"(COM(2008)652Final/2, p.2).TheCommunityStrategicGuidelinesonCohesion(CSGs)adoptedbytheCouncilon6 October 2006for the period 2007-2013 explicitly encourage Member States and regions to promote strong clusters as part of their economic reform strategies. The European Commission recommended improving trans-national cluster cooperation, promoting the excellence of cluster organization and ensuring inclusion of SMEs in cluster programme as essential elements of policies aimed at building world-class clusters. Many policy initiatives have been adopted in the European countries since then, both at national and at regional level, and this special issue intends to provide a well-documented source ofinformation onthis variety. The issue gathers together different articles covering a wide range of countries and cases, providing evidence that under the same label of cluster strategy, policies have taken various forms and focuses, and have had different effects. The firstcontribution is anillustrationof the diversity of thecluster policies;itisdedicated to the variety ofregional cluster policies in afederal state, Germany, and to policy learning fromotherexperiences. Thepurposeofthisspecialissueonclusterpoliciesisindeedtolearn from multiple experiences. Anumber of contributions show the changes occurred in the cluster policies over time. ThisisthecaseofKorea,France,Italy,Germany,BasqueCountry,andsomehowUK,where the cluster policies begin to spread in the 90's. In all these countries the cluster strategies change their labels over time, and in many cases they also modify their content. Policy objectivesandgeneralpolicysettingsalsochange,andinsomecases,suchasinFranceorin Italy,the "old" cluster policies seemtobe atoddswith thenew strategies.Insomecases, such as in the UK, the reforms of regional development agencies that were in charge of cluster strategies introduce further complexity. Other contributions relate to some countries and regions in which cluster policies have been implemented in recent times. This is the case of, China, Russia, Serbia, Tunisia and Turkey where cluster strategies emerge during the 2000s.Although the experiences ofthese countries are still young, some contribution tries to provide some evidence of the results achieved so far, as wellassomeanalysisof themoregeneralcontextinto whichthese policies insert.Inallthesecases,clusterpoliciesareinstrumentstopromotethedevelopmentandthe innovativepotential of a region.Inthe caseof Chinatheseobjectives combine with the aimof achievinga more balanced development. Last but not least, the i-topic associated to this issue draw lessons from a personal experience related to the implementation ofthe so-called third mission ofuniversities in the Italian industrial district.