Chronic sleep disturbance is a common problem in preschool children. Prescription and non-prescription sedatives provide short-term palliative relief. Behavioral extinction by withdrawal of parental attention is enduringly effective but may be distressing short-term because of postextinction bursts of intense activity by the child. This study evaluated the effects of combining extinction and sedative medication (trimeprazine tartrate), prescribed in a reducing dose over the first 10 days of extinction. Control groups received either extinction alone or a placebo administered double-blind. After baseline, all subjects reduced their sleep disturbance to low levels, the extinction and placebo groups declining slowly, the medication group abruptly. These gains were maintained at follow-up. Measures of infant security and maternal anxiety showed improvements with treatment.