Abstract
Despite robust evidence that bilingualism does not hinder language development in autistic children, service providers continue advising multilingual families to adopt English as their home language. This research-to-practice gap severs intergenerational cultural transmission and compromises parent-child communication. This perspective paper examines how historical misconceptions linking bilingualism with cognitive deficits became embedded in autism intervention practices. We analyze how intersecting ideologies of ableism and racism co-construct deficit-lens perspectives, and how policies rooted in White Mainstream English hegemony, organizational barriers, and assimilationist paradigms undermine multilingual families' linguistic practices. Research shows autistic children successfully acquire multiple languages, and heritage language maintenance is essential for ethnic identity, family relationships, and well-being. Yet the systematic exclusion of non-English speakers from intervention research has created an evidence base that reinforces monolingual practices. This disconnect represents a fundamental refusal to dismantle structures positioning English monolingualism as the default standard. Culturally sustaining autism interventions must promote additive bilingual environments, recognizing language as the medium through which children access family histories, spiritual practices, and belonging. Adopting a neuroaffirming framework centering well-being over compliance requires cultural humility and self-reflection about how our experiences shape clinical work. We call for research investigating best practices that honors, protects, and sustains heritage language environments-evidence urgently needed to reshape outdated policies restricting home language instruction.