Elevated caregiver strain is common and linked to poor health in parents of children with autism. Yet, little research has examined caregiver strain longitudinally and in geographically diverse samples of parents whose children have autism. This study aimed to (1) examine change in caregiver strain and (2) determine correlates of improved caregiver strain in North American parents of children with autism. This was a secondary analysis of data from the Autism Treatment Network Registry Call-Back Study, conducted from 2015 to 2017 on a random sample of children with autism spectrum disorder at 12 clinical sites in the United States or Canada. Child assessments and parent-reported questionnaires were completed at two time points 1 year apart. Caregiver strain was assessed with the Caregiver Strain Questionnaire. In total, 368 children had caregiver strain data at both times. Mean caregiver strain in parents did not significantly change between Times 1 and 2 (mean difference = 0.05, t(360) = 0.1, p = 0.92). Improved caregiver strain between Times 1 and 2 was associated with improved child adaptive functioning and externalizing problem behaviors. Caregiver strain was persistent and multi-factorial. Parent training to manage challenging child behaviors and adaptively cope may benefit this vulnerable parent population.