This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book aims to identify the ways working time has developed in recent years, evaluating the significance of the changes and highlighting the major factors which have influenced both change and stability in working time patterns. It includes a consideration of the work-sharing debate and in particular the arguments for and against work-sharing, the shortcomings of those arguments and the results of recent work-sharing initiatives and working hour's changes. The book examines some of the main shiftwork patterns in operation, the health and social implications of shiftwork, the recent development of new patterns and the overall prospects for the growth of shiftworking. Most Western industrialized societies have been witnessing fundamental changes occurring both in their industrial structures and within individual workplaces. The most important changes in working time are occurring not in a single country but in a variety of national contexts.