A look at two aspects of intimacy, both over the centuries and over the span of an individual lifetime. To examine how we learn to "affiliate" and love, Stefoff explains such classic theories as those of Freud, Bowlby, Piaget, Fromm, Maslow, and Erikson; she also brings in the ideas of psychological self-help writers: e.g., Lillian Rubin's notion of the places of "friends of the road" (briefly determined by circumstance) and "friends of the heart." Friendships discussed range from the earliest (parents, siblings) to imaginary, best, and group membership; differences in expectations in various societies are compared. Adolescence is recognized as a time of experimentation. Types of love described include spiritual, courtly, romantic, homosexual and heterosexual: there are up-to-date distinctions like that between "limerence" (falling in love) and long-term relationships. The minimal information on sex seems awkwardly tacked on; but, then, it is not the subject here. Well suited for high-school psychobiology or sociology courses, this interesting volume of "The Encyclopedia of Health" should help teens understand why their attachments change with time. Appendix of organizations; bibliography; glossary; index.