This book presentshigh-quality original contributions on new software engineering models,approaches, methods, and tools and their evaluation in the context of defenceand security applications. In addition, important business and economic aspectsare discussed, with a particular focus on cost/benefit analysis, new businessmodels, organizational evolution, and business intelligence systems. Thecontents are based on presentations delivered at SEDA 2015, the 4thInternational Conference in Software Engineering for Defence Applications,which was held in Rome, Italy, in May 2015. This conference series represents atargeted response to the growing need for research that reports and debates thepractical implications of software engineering within the defence environmentand also for software performance evaluation in real settings throughcontrolled experiments as well as case and field studies. The book will appealto all with an interest in modeling, managing, and implementing defence-relatedsoftware development products and processes in a structured and supportable way.