This Advisory highlights how mental and substance use disorder (SUD) treatment programs can better serve people with physical and cognitive disabilities and SUDs and/or serious mental illness (SMI). The most current prevalence data, from 2016, estimated that 61.4 million noninstitutionalized U.S. adults had one or more disabilities. SMI and co-occurring SUDs are generally considered disabilities under federal disability rights laws. This publication is not intended to provide guidance on complying with federal, state, or local disability rights laws. This Advisory includes some recommendations that are required, may be required, or may exceed the requirements of the federal, state, or local disability rights laws.