Understanding the types of intervention practices familiar to transdisciplinary autism spectrum disorder providers may be critical to characterize and optimize "usual care" for common clinical concerns (e.g. internalizing, externalizing, and social challenges) among school- and transition-age autistic youth. We assessed if there is an underlying factor structure to expert providers' familiarity with such practices, and if characteristics of experts (discipline, years' experience, and school setting) and/or their clients (age and intellectual disability) predicted these factors. Fifty-three expert providers rated their familiarity with 55 practices via an online Delphi poll. Exploratory structural equation modeling identified latent factors of familiarity, which were regressed onto provider and client variables to identify predictors. Four factors emerged: two approaches (cognitive and behavioral) and two strategies (engagement and accessibility). Cognitive approaches were associated with practicing outside school settings and treating clients without intellectual disability, behavioral approaches with practicing in schools and the disciplines of clinical psychology and behavior analysis, engagement strategies with practicing outside school settings, and accessibility strategies with more years in practice. Findings suggest expert transdisciplinary autism spectrum disorder providers are familiar with many of the same approaches and that differences in knowledge are predicted by their discipline, treatment setting, experience, and work with youth with intellectual disabilities. [This article was co-authored with the UCAS Consortium including: Amy Drahota, Latha Soorya, Allison Wainer, Matthew D. Lerner, Lauren J. Moskowitz, Elizabeth Cohn, and Connor M. Kerns.]