The purpose of this study was to assess pediatric nurses' knowledge of children's psychosocial development as affected by the child's illness and hospitalization and as related to provision of nursing care. A 25-item questionnaire was designed to measure pediatric nurses' knowledge of child development on the conceptual dimensions of knowledge of play development, concept of time, awareness of surgical preparation, and psychosocial and psychosexual development across the four stages of childhood (infancy, toddlerhood, preschool, and school-age). Validity of the instrument was assessed by submitting it to a panel of pediatric nursing experts. A total of 70 subjects at four hospital facilities in the Los Angeles area participated in the study. None of the attribute variables (age, level of education, or type of hospital unit) was significantly related to level of knowledge as revealed in percentage of correct/incorrect responses. Results indicated that a knowledge gap exists in content areas related to the psychosocial development of children. (A selected sample of items from the psychosocial questionnaire is included.) (RH)