ABSTRACT This study is a randomized clinical trial investigating the efficacy of a sensory adapted dental environment (SADE) compared to a regular dental environment (RDE) to decrease physiological anxiety, distress behavior, perception of pain, and discomfort during a dental cleaning in children with Autism Spectrum Disorder (ASD). The SADE procedure modifies the degree and type of visual, auditory, and tactile stimulation that children experience during dental cleanings. In this crossover design, the SADE will be compared to a RDE in a group of children with ASD with visits occurring four-six months apart. The outcome variables are physiological anxiety as measured by electrodermal activity (EDA) and child negative responses (distress behavior, perception of pain, sensory discomfort) exhibited by the child during dental cleaning visits. Analyses will include repeated measures ANCOVA models to examine the differences in the within- group factor (environment) in the ASD groups. Participants will be 220 ethnically diverse children with ASD aged 6-12 years. All children will be Southern California residents. Participants will be recruited primarily from Children’s Hospital Los Angeles (Dental Clinic, University Center for Excellence in Developmental Disabilities, Boone Fetter Clinic, AltaMed General Pediatrics Service) and the Los Angeles Unified School District (LAUSD), so the sample in this study will likely over-represent low income Hispanic/Latino families who are at high risk for poor oral health. Consistent with ASD prevalence statistics, we anticipate a ratio of approximately four boys for every girl in the sample.