Birth order, and number, age, and sex of siblings were related to social adjustment in a group of 79 psychiatric patient soldiers and a group of 117 normal soldiers, with age of Ss and socioeconomic status held constant. It was found that: (a) Psychiatric patients were more often "only" children than were normal Ss. Character and behavior disorders tended to be "only" children more often than schizophrenics or neurotics. (b) In families of 5 and more siblings, normals more often than patients came from the first and last birth positions. (c) Patients who were judged to have a good prognosis, and married patient and normal Ss, more often than patients with a poor prognosis, and unmarried patient and normal Ss, tended to come from large families. (d) Married patients who were returned to duty, more often had younger brothers than patients who remained single, or patients who had to be discharged from the service. (PsycINFO Database Record (c) 2006 APA, all rights reserved)