Given the importance that both member states and European Union institutions play in the development of nanotechnology regulatory policies at the European level, this study focuses on the analysis of policymaking patterns across countries and the between member states and EU institutions. In particular, this research explores three case studies, Germany, the UK, and the Netherlands, as leaders in nanotechnology regulation. High concentrations of nanotechnology firms in both the UK and Germany have made them natural leaders in European policy development. However, policymaking within both states differ dramatically with Germany pursuing much more open policy strategies that incorporate public interests and the UK pursuing a closed policy process which tends to favor industrial interests over broader societal and environmental groups. Due to high levels of interaction with EU agencies and a strong emphasis on environmental sustainability, health, and safety regulation the Netherlands has also emerged as an important actor in nanotechnology policy development despite a substantially smaller number of nanotechnology firms. This research helps to identify why some countries have much more developed frameworks to address the potential security, health, and environmental risks of nanotechnology than others. Ultimately, these case studies emphasize the importance that economic, social, and political interests and existing institutional structures play in explaining policy variation across states as well as the different positions states have taken in nanotechnology regulatory development in Europe.