Introduction: We examined the development of anxiety in youth with or without intellectual disabilities (ID). We also examined the effects of child delay status, temperament, ethnicity, and negative parenting on anxiety symptom trajectory. Method: Participants were 177 families in (blinded). We employed latent growth curve modeling to examine the trajectory of anxiety symptoms (ages 3-13 years) and to examine the individual and interactive effects of variables in predicting age 3 anxiety and change in anxiety. Results: Anxiety symptoms increased over time. Children with ID demonstrated higher levels of anxiety compared to typically developing (TD) children. Social fearfulness was positively associated with anxiety at age 3. Anxiety increased at a slower rate in Latino children. Negative parenting positively predicted rate of change in anxiety for children with ID but not TD children. Conclusions: These findings inform early intervention targets for culturally diverse families of children with or without ID.