Kinship is the primary organizing principle in human relations. The notion of psychological kinship is introduced to account for those instances where persons treat certain genetically unrelated significant others "as if" they were family. As in other human relations, psychological kinship is assumed to play an important moderating role in client-therapist and helpee-helper relations in the helping professions. Various implications of psychological kinship for professional helping, "low" and "high" kinship approaches, and characteristics of the "kinship therapist" are discussed.Kinship is the primary organizing principle in human relations. People do not simply relate but rather they relate and interact in adaptive and predictable ways governed largely by their bioevolutionary mammalian and primatological natures on the one hand, and their sociocultural learning experiences on the other (Bailey, 1987;Fox, 1975). The anthropologist Fox (1972) says, "Kinship systems link us more directly to the beasts than any other subsystems of human culture in that they are in effect breeding systems" (p. 284). The basic elements of kinship in advanced mammalsThe author thanks William Hawkes and Elaine Monnier for help in generating items for the Kinship Scale, Gus Nava for conducting the pilot study and analyzing the data, and Rees Chapman for additional help in data analysis. Appreciation is also expressed to Seymour B. Sarason for his comments on an earlier version of this article.