Length of stay in psychiatric inpatient units has received increasing attention with the external pressures for treatment cost-effectiveness and evidence that longer hospital stays do not appear to have significant advantages over shorter hospital stays. This study examined the relationship between length of psychiatric hospital stay and demographic, family, diagnosis and presenting problems, cognitive functioning, current treatment, and previous mental health treatment variables. Subjects included 200 children and adolescents recently discharged from a state psychiatric hospital. Regression analyses indicated the best groups of predictor variables of length of inpatient psychiatric hospital stay in children and adolescents were the demographic variables and the diagnostic and presenting problem variables. The poorest groups of predictors were the family variables and the cognitive functioning variables. Awareness of factors contributing to the length of hospital stay may assist clinicians in formulating better treatment goals. The findings of the present study suggest many youth would benefit from treatment focused on attention-deficit problems. (ABL)