This book develops and describes a general methodology that can be applied to any complex human activity (activity with a non-trivial, multi-level internal structure). The structural components of complex activities are considered, and their logical, cause-and-effect, and process structures are functionally described. Considerable attention is paid to organization and management, uncertainties, and the lifecycles of activities, as well as the actors, subject matter, resources, knowledge, and methods involved. Several typical examples are used throughout the text to illustrate the implementation of common approaches involving the functioning of work groups, organizational units, projects, and organizations in general: a retail bank, an aircraft manufacturer, a fire department, and a nuclear power plant. In addition, the book employs a system of connected technical models, in order to ensure that the results are of practical applicability for both experts on the ground and scholars engaged in research on the general principles of how activities (practical, scientific, etc.) are organized or on the management of socio-technical systems.