Children with ASD receive a multitude of educational, medical, and therapeutic services. At the onset of the COVID-19 pandemic, all of these services came to a complete halt following strict lockdowns. Many services have resumed in a hybrid format using face to face and virtual modes of delivery. This study describes findings from the COVID-19 impact survey administered at the onset of the pandemic in a subgroup of families from the SPARK cohort (N = 6393), one of the largest ASD cohorts in the US. The differential early impact of COVID-19 on various subgroups of children with ASD and their families was examined. Caregivers of children and adolescents with ASD between 19 months and 18 years completed an online survey inquiring about the impact of COVID-19 pandemic on access to services, parent concerns about the same, impact on child's ASD-related behaviors, child, and parent mental health, and the benefits/potential benefits of online/future online services. Analysis revealed that certain demographic (age, income/SES) and child-related factors (repetitive behaviors, language, functional, cognitive, and motor impairments, and child's understanding), as well as parent's past mental health were associated with/predicted greater service disruptions, greater ASD-related behaviors, and greater negative impact on parent mental health. In conclusion, younger children, children from low-income families, and children with greater impairment severity (more severe repetitive behaviors, language, cognitive, function, language, and motor impairments) were more negatively impacted by the pandemic through service disruptions, increased ASD-related behaviors, parent health/family impact, and found online interactions to be less beneficial. LAY SUMMARY: The SPARK study impact survey shows that at the onset of the COVID-19 pandemic, parents reported significant service disruptions, negative impact on their child's ASD-related behaviors as well as their own mental health; which was greater in families with younger children, children with greater ASD severity, and children from low-income families. Majority of families did not report significant benefits of online services whereas some families did. Low-income families were hopeful about receiving benefits through future online services. Overall, these findings have important implications for future clinical care delivery and healthcare policies to ensure that healthcare services are not interrupted during a potential resurgence of COVID-19 or other pandemics. A combination of in-person and online healthcare and family support services must be implemented to prevent negative health impacts in the future.