There has been much discussion about the importance of networks for regional economic development and knowledge dissemination. However, the inflationary use of the notion "networks" is often based on rather metaphorical, at worst fuzzy meanings. This book explores ways for more rigorous research on knowledge networks, critically discussing quantitative social network analysis. A theoretical framework for meaningful interpretations in quantitative network research is developed. Afterwards, the monograph links social network analysis to research on localised knowledge spillovers. Here the role of communities and networks of knowledge workers is investigated. The book illustrates how social network analysis can provide fruitful perspectives for further research on knowledge flows.