Revision with unchanged content. Social Network Analysis comprises a toolbox of scientific methods for investigating relations between actors. The author of this book argues that even recognized scientists apply this popular research methodology without seriously considering its pitfalls. His study demonstrates how certain factors can interfere with the processes of data collection and data analysis, and therefore lead to invalid or unreliable results. The book begins with an introduction into the methods of social network analysis and then presents one of the most comprehensive discussions of literature on the issue of its validity. Afterwards it describes the author’s study, which applies a simulation technique to investigate the influence of various factors on common measures in social network analysis. The results presented at the end give important hints concerning the proper use of network analysis. The book addresses users and students of social network analysis in sociology, political sciences and economics.