The development and diffusion of offshore wind energy technology is important for European energy policy. However, the large potential does not automatically lead to a large share in future energy systems; neither does an emergent stage of technological development automatically lead to success for companies and the related economic growth and growth in employment. Recent insights in innovation studies suggest that the success chances of technological innovations are, to a large extent, determined by how the surrounding system (the innovation system) is built up and how it functions. Many innovation systems are characterized by flaws that hamper the development and diffusion of innovations. These flaws are often labelled as system problems or system challenges. Intelligent innovation policy therefore evaluates how innovation systems are functioning, tries to create insight into the systems’ challenges and develops policies accordingly. This report assesses the European offshore wind innovation system based on insights from four countries: Denmark, the UK, the Netherlands and Germany. We use the Technological Innovation System (TIS) approach to analyse the state and functioning of the system at the end of 2011. Based on the analysis we identify four types of systemic challenges: (i) actor-related such as deficiency of engineers; (ii) institutional, e.g. non-aligned national regulatory frameworks; (iii) interaction-related like poor transferability of scientific knowledge to specific contexts of application and; (iv) infrastructural such as poor grid infrastructure. We suggest the challenges require a systemic, coordinated policy effort at a European level if the system is expected to contribute to the goals of climate change reduction and stimulation of green growth