This article offers an introduction to grid-group cultural theory (also known as grid-group analysis, Cultural Theory or theory of socio-cultural viability), an approach that has been developed over the past thirty years in the work of the British anthropologists Mary Douglas and Michael Thompson, the American political scientist Aaron Wildavsky, and many others. This assessment begins with a presentation of the main claims of the theory, distinguishing two characteristic breads of grid-group cultural theory, in the one it is conceived as a heuristic device, in the other it is seen as a full explanatory theory. This brief is followed by a discussion of the typology generated by the theory. This includes a presentation of the two dimensions of sociality it posits, the cultural map they produce, as well as the four (or five) cultural types derived from them and their designations. The article proceeds with a discussion of key issues including the incorporation of other typologies (such as the one developed to analyse myths of nature), the relations between cultures or rationalities and several methodological issues. Finally the article introduces the contributions to this special issue of the GeoJournal.