The study examined factors impacting caregiver burden following diagnosis of an autism spectrum disorder (ASD). Primary caregivers of children diagnosed with an ASD within the past 6 months (n = 78) were assessed on variables thought to influence outcomes associated with family stress as proposed within the double ABCX model of family adaptation, i.e., severity of autistic symptoms, additional life demands, social support, appraisal, and coping strategies. Burden was measured across three domains: individual caregiver, marital relationship, and the family as a whole. Most families reported high levels of burden following their child's diagnosis. Symptom severity, additional pile-up demands, social support, and the use of passive avoidant coping strategies were strong and consistent predictors of increased burden. (Contains 1 figure and 3 tables.)