Software design is becoming increasingly complex and difficult as we move to applications that support people interacting with information and with each other over networks. Computer supported co-operative work applications are a typical example of this. The problems to be solved are no longer just technical, they are also social: how do we build systems that meet the real needs of the people who are asked to use them and that fit into their contexts of use. We can characterise these as wicked problems, where our traditional software engineering techniques for understanding requirements and driving these through into design are no longer adequate. This book presents the "Locales Framework" - and its five aspects of "locale foundations", "civic structures", "individual views", "interaction trajectory" and "mutuality" - as a way of dealing with the intertwined problem-solution space of wicked problems. A locale is based on a metaphor of place as the lived relationship between people and the spaces and resources they use in their interactions. This text provides a coherent mediating framework for ethnographers, designers, and software engineers to facilitate both understanding requirements of complex social situations and designing solutions to support these situations in all their complexity.