Inclusion Criteria:  Confirmed autism spectrum disorder diagnosis Admitted as an inpatient to a behavioral unit prior to informed consent Displays episodes of moderate to severe agitation  Exclusion Criteria:  Hypersensitivity to olanzapine Currently diagnosed with a genetic or other syndromic form of neurodevelopmental disorder Seizure in the past 6 months History of severe head trauma, stroke, endocrine disorder, or cardiovascular disease History of hypotension Currently on a chronic dose of olanzapine Currently taking fluvoxamine