In a volume such as this, devoted to family spychotherapy, the position occupied by sexual function and dysfunction is a powerful but ambiguous one. When family therapy is discussed, the immediate image is of a therapist dealing with family members of at least two generations - typically the nuclear family with young children and two parents. Such a family could not exist unless sexual intercourse had taken place, and clearly all family members have their own sexual wishes and fantasies. On the other hand, sex is not a subject easily talked about between members of different generations, and can thus remain a hidden but powerful force influencing family dynamics. It seems to me that to formulate a family's problem without finding out the degree of sexual satisfaction in the parents' marriage is leaving out an important source of information. One could even postulate that a good sexual relationship, along with a sensible attitude to sex, between the parents is an indispensable prerequisite to the rearing of children in a balanced way. Again, one can cite many examples of families where sexual frustration or inhibition in the parents has led to sexual dysfunction in later years in the children.