Background and AimsAnxiety and depression symptoms are common among autistic youth, yet little is known about the pattern and relationship of their trajectories from childhood into adolescence, a period of increasing social and academic demands.MethodsThis study used parallel process latent growth curve models to examine joint trajectories, including initial levels and rate of change in caregiver-reported depression and anxiety symptoms across age 7–16 within an inception cohort of autistic yout