Establishing Fidelity of Neurodiversity-Affirming Interventions - Project Summary Interventions to support clinical and behavioral needs of autistic people are among the most resource- intensive in any field. While it is crucial to advance the use of empirically-supported interventions for this population, it is yet more pressing to understand factors that drive intervention decision-making among practitioners and families regardless of empirical status. With the rise of the neurodiversity movement, which deprioritizes the goals of normalizing behavior or eliminating autism, there has been a rapidly-growing appreciation from stakeholders for interventions consonant with such values, grounded in the experiences of autistic people and other members of the autism community, while still impacting important outcome domains. Thus, the aspiration to implement so-called neurodiversity-affirming interventions (NAI) has become a touchstone in the autism stakeholder community as a marker of value and utility. Indeed, many practitioners are changing the way their practices are advertised to highlight their purported use of NAIs, and families are increasingly considering the NAI label when making decisions about the services they choose for their children. This can directly impact whether families elect to engage in any intervention at all, irrespective of empirical status. However, while NAI is quickly emerging as a new practice domain, no consensus exists about what constitutes a NAI. With scant empirical or theoretical literature, there is no operationalization of the term, and vast space for ambiguity, creating a “carts before horses” problem. Indeed, this has created a crisis for the field, making it impossible to ask empirical questions about whether NAIs impact target outcomes, how they align (or do not) with evidence-based practices, who is doing NAIs, and what features of NAIs cohere as an identifiable practice set. Thus, a tool to measure fidelity of NAI implementation is urgently needed. The goal of this project is to produce such a measure. This project aims to leverage qualitative interviews of relevant experts (autistic individuals and caregivers) to establish a pool of items indicating what they see as the outcomes most affected by NAIs. It will then draw from a national sample to establish a comprehensive, NAI measure that also group-specific variation by of a) autistic individuals, b) caregivers, and c) practitioners, using the initial item set by implementing a multi-round Delphi poll approach to establish consensus. Finally, this study will administer a large national survey of practitioners across clinical and behavioral disciplines that work with autistic individuals, examining internal consistency of the Fidelity measure and its 3 subscales (autistic individuals, caregivers, practitioners), as well as convergent and divergent validity of the measures across practitioner groups, considering demographics, training, outcome targets, and discipline. This work will provide a foundation for future study of NAI, providing a tool to examine the discrete and additive effects of NAI implementation on outcomes in a wide array of evidence-based and community-derived intervention settings.