Book excerpt: Systems theory is the basic theoretical model underlying most contemporary family therapy. In this accessible introduction, the author traces how systems theory gave rise to family systems theory, outlines the basic propositions of family systems and links it both to other family theory literature and to clinical practice. Among the topics covered are relational space, family boundaries, family stratification and child socialization. Family meanings and such shared realities as family folklore, stories, myths and memorabilia are discussed. Family rituals are also explored.