A wholly creditable, nicely integrated compendium of past and recent research concerning the effects of sibling birth order on personality and vocational, social, sexual, and marital choices. Forer, a psychotherapist, has drawn upon her own clinical observations, as well as landmark studies such as those of Adler and Helen Koch, to evolve birth-order profiles--which do contain some admitted contradictions. The broad profiles may sound familiar: the only child is apt to be dominant, verbal, a perfectionist, eager to placate authority; the oldest or older child tends to be more conscientious, to achieve more scholastically but have a lower anxiety threshold; the second sibling and other ""middle children"" are better negotiators and friendlier. But there are many variants and determinants, to which Forer gives painstaking attention. The sex of siblings strongly affects the birth-order influence; for example, the birth of a second child often prompts sibling #1 to shift allegiance from the occupied mother to the father--less a problem for a boy than a gift, but the father's response may offer serious trouble for either. Forer sifts through the seemingly infinite combinations of siblings with each other and their parents; and she uses a multitude of case histories to point out the value of birth-order studies in therapy. A responsible, richly informative scrutiny of an area not usually given much attention in the popular literature of psychology.