In aiming to understand and model peoples? out-of-home movements, the academic field of transport planning is confronted with two major challenges; firstly, leisure travel is increasing in importance and is more complex and variable than work-related travel; and secondly, traditional aggregated transport models do not include any information on peoples? social interactions or their personal social networks. These two main factors have driven transport planners to focus on peoples? interaction and their social network. Providing an overview of selected exemplary studies, this volume addresses the overlap between transport planning and methods of social network analysis; applied methods of social network analysis and related empirical results; and current challenges and new research questions in this field.