The primary aim of family psychiatry is to demonstrate how the mental health of family members is interrelated. It is a study in which aspirations have outstripped techniques, possibly because research workers have attempted to apply the subtlety of clinical insights to details of family dynamics. Yet only confusion can follow such attempts while basic general data are still lacking; and as Post's (1962) survey illustrates so clearly, our present certain knowledge, despite great and continuing labour, remains exiguous.