Objective:The authors examined how the COVID-19 pandemic affected the behavioral health of people with intellectual and developmental disabilities (IDD).Methods:A modified version of the Coronavirus Health Impact Survey–Adapted for Autism and Related Neurodevelopmental Conditions was sent to the authors’ clinical networks and IDD-affiliated organizations from March to June 2021.Results:In total, 437 people with IDD or their caregivers responded to the survey. Diagnoses included intellectual disability (51%) and autism spectrum disorder (48%). More than half (52%) of respondents reported worsened mental health. Losing access to services correlated with declining mental health. Interventions suggested to improve behavioral health included more time with friends and family (68%), more time outdoors (61%), and access to community activities (59%).Conclusions:COVID-19 affected the behavioral health of individuals with IDD. Survey results highlight the opportunity to leverage physical activity and pandemic-safe social supports as accessible means to mitigate gaps in services.