The Interagency Autism Coordinating Committee (IACC) is a federal advisory committee that advises the Secretary of Health and Human Services (HHS) on issues related to autism spectrum disorder (ASD). It was established by the "Children's Health Act of 2000" (Public Law 106-310), reconstituted under the Combating Autism Act of 2006 (CAA; Public Law 109-416), and was most recently renewed under the "Autism Collaboration, Accountability, Research, Education, and Support (CARES) Act of 2019" (Public Law 116-60). One of the statutory responsibilities of the IACC under the CAA and subsequent authorizations is the development of a strategic plan for autism, to be updated annually. The "Autism CARES Act of 2019" requires that the strategic plan address the "conduct of, and support for, autism spectrum disorder research, including as practicable for services and supports." With each update of its "Strategic Plan," the IACC re-evaluates the needs of the autism community and the best ways to achieve progress. The "2021-2023 IACC Strategic Plan for Autism Research, Services, and Policy" summarizes current understanding of autism-relevant topics and addresses current gaps and opportunities in autism research, services and supports, and policy. As in previous years, the "IACC Strategic Plan" is organized around seven general topic areas that are represented in the Plan as community-focused Questions. Each question is assigned a chapter in the "Strategic Plan" that provides an Aspirational Goal, or long-term vision for the question; a description of the state of the field; the needs and opportunities in research, services, and policy; and three broad Objectives. In this edition of the "IACC Strategic Plan," the Objectives from the "2016-2017 IACC Strategic Plan" have been updated and renamed as "Recommendations." The 24 total updated Recommendations in this "Strategic Plan," including the new equity Recommendation and the Budget Recommendation, address critical gaps and potential opportunities for advancement that were identified by the IACC. The IACC's goal during the development of this "Plan" is to present a collective voice detailing the current status and future goals of autism research, services, and policy. [For the "Interagency Autism Coordinating Committee Strategic Plan for Autism Spectrum Disorder, 2018-2019 Update," see ED608308.]