Senate Bill (SB) 163 would alter the current law that requires coverage of behavioral health treatment (BHT) for autistic spectrum disorder (ASD). SB 163 would expand the definition of BHT to include treatment modalities based on developmental theory, would make technical changes to definitions related to network adequacy, would prohibit denial of coverage based on either lack of parental/caregiver involvement or treatment setting time, or location, and would end an exemption related to Medi-Cal. CHBRP estimates that of the 24.5 million Californians enrolled in state-regulated health insurance, all have insurance that would be subject to SB 163. There is evidence of effectiveness for BHT modalities based on behavioral theory, based on developmental theory, or based on both. There is evidence of effectiveness for BHT delivered in multiple settings. Although outcomes may improve with parent/caregiver involvement, there is evidence that BHT is effective when furnished only by providers. [This report was prepared by the California Health Benefits Review Program.]