This bill seeks to significantly improve the quality of special education and related services for children and youth who are deafblind. It establishes a comprehensive definition for "deafblind" individuals, encompassing those with concomitant hearing and visual impairments that impede information access, cause severe communication challenges, and adversely affect educational performance. The legislation mandates that states identify, locate, and evaluate all deafblind children, ensuring they receive appropriate services even if classified under another disability category, and requires data collection on these children. A key provision is the inclusion of intervener services , provided by qualified interveners, within the definition of related services under the Individuals with Disabilities Education Act (IDEA). States will be required to submit an addendum to their IDEA plans, detailing how they ensure comprehensive evaluations by qualified professionals, sufficient personnel, and the provision of necessary special education and related services for all deafblind children. This addendum must specifically address language development, communication access, and family support, developed in consultation with experts. The bill further strengthens evaluation requirements, specifying that assessments for deafblind children must cover language and communication proficiency in their preferred mode, with qualified personnel involved. Individualized Education Programs (IEPs) must also address specific language and communication needs, including tactile sign language. Additionally, the legislation calls for the development of policy guidance for parents and educators, the establishment of regulations defining "deafblindness" and "intervener services," and expanded personnel development to train qualified teachers of deafblind children, interveners, and early intervention specialists.