Introduction describes the main aim of the volume as to present a novel approach to the study of social evolution. This approach is based on a look at, and analysis of social evolution through the evolution of social institutions associated with the rise and development of social complexity. Evolution is defined as the process of structural change. Within this framework, the society, or culture, is seen as a system composed of a great number of various social institutions that are interacting and changing. As a result, the whole structure of society is changing, that is evolving. Evolution does not have any particular direction, as any significant (that is, transforming the societal structure in any direction) change is evolutionary. Introduction gives an outline of the history of the notion of social institution and its conceptualization, and describes social institutions’ main characteristics and functions. It also summarizes the volume’s theoretical chapters and case studies.