We examined parent activation in families with autistic children over time. Activation is one's belief, knowledge, and persistence in obtaining and managing one's care (e.g., patient activation) and others (e.g., parent activation) and is associated with better outcomes. Four aims were examined: the associations between baseline parent activation and follow up treatment/outcome, between changes in activation and changes in treatment/outcome, differences in activation and treatment/outcome across demographic groups (e.g., gender, race, ethnicity, and income) and comparison of results using three different assessment approaches of parent activation, the Guttman scale (standard approach) and two factor subscales (Yu et al., in J Autism Dev Disord 53:110-120, 2023). The first factor tapped into behaviors aligned with highly active, assertive parental actions (Factor 1: Activated). The second tapped into behaviors representative of uncertainty, passivity, being overwhelmed, with growing awareness of the need for activation (Factor 2: Passive). Findings varied with assessment methods applied. The two subscales assessment approach produced the strongest effect sizes. Baseline activation was related to "improved" child outcomes at follow-up for Factor 1: Activated and to "poorer" child outcomes at follow-up for Factor 2: Passive. Changes in activation were unrelated to changes in treatment/outcomes. Outcomes differed based on the activation assessment approach used. Against expectations, activation remained the same over time. Further, no differences in outcomes were observed based on race, ethnicity, or family income. The results suggest that parent activation may behave differently than patient activation based on prior studies. More research is warranted on activation of parents of autistic children.