Activation refers to patients' belief, knowledge, ability, and persistence to manage care. The concept is adapted to parent activation in developmental disorders. This study examined the psychometrics of the Parent Activation Measure for Developmental Disabilities (PAM-DD) and factors related to parent activation in ASD. Data from 658 caregivers of children with ASD in the Autism Treatment Network Registry Call Back Assessment study were analyzed. The actual ordering of the scale items was inconsistent with the assumptions of a Guttman scaling. Factor analysis revealed two PAM-DD factors. Lower child symptom severity was related to higher Factor 1 and lower Factor 2 activation. Future studies should use caution when treating PAM-DD as a Guttman and unidimensional scale.