Military command and control is not merely evolving, it is co-evolving. Technology is creating new opportunities for different types of command and control, and new types of command and control are creating new aspirations for technology. The question is how to manage this process, how to achieve a jointly optimised blend of socio and technical and create the kind of agility and self-synchronisation that modern forms of command and control promise. The answer put forward in this book is to re-visit sociotechnical systems theory. In doing so, the problems of 21st century command and control can be approached from an alternative, multi-disciplinary and above all human-centred perspective. Human factors (HF) is also co-evolving. The traditional conception of the field is to serve as a conduit for knowledge between engineering and psychology yet 21st century command and control presents an altogether different challenge. Viewing military command and control through the lens of sociotechnical theory forces us to confront difficult questions about the non-linear nature of people and technology: technology is changing, from platform centric to network centric; the interaction with that technology is changing, from prescribed to exploratory; and complexity is increasing, from behaviour that is linear to that which is emergent. The various chapters look at this transition and draw out ways in which sociotechnical systems theory can help to understand it. The sociotechnical perspective reveals itself as part of a conceptual toolkit through which military command and control can be transitioned, from notions of bureaucratic, hierarchical ways of operating to the devolved, agile, self-synchronising behaviour promised by modern forms of command and control like Network Enabled Capability (NEC). Sociotechnical system theory brings with it a sixty year legacy of practical application and this real-world grounding in business process re-engineering underlies the entire book. An attempt has been made to bring a set of sometimes abstract (but no less useful) principles down to the level of easy examples, design principles, evaluation criteria and actionable models. All of these are based on an extensive review of the current state of the art, new sociotechnical/NEC studies conducted by the authors, and insights derived from field studies of real-life command and control. Time and again, what emerges is a realisation that the most agile, self-synchronising component of all in command and control settings is the human.