Preschoolers with elevated anxiety symptoms are at high risk not only of developing more severe mental health disorders in later life but are also apt to respond more poorly to intervention if they present with comorbid disruptive behavior. Because early signs of anxiety disorders may not be recognized as such in preschool settings, many children selected for Tier 2 interventions that target externalizing problem behaviors may also have co-occurring anxiety symptoms and disorders. The First Step to Success intervention has recently been adapted for preschoolers with externalizing behaviors and was found to be efficacious in a randomized controlled trial. The current report examines effects of the First Step intervention on a subsample of 38 preschoolers with comorbid anxiety symptoms. Compared to usual-care controls, preschoolers who were assigned to the First Step intervention demonstrated medium-to-large effects in reducing externalizing behavior and improving social functioning outcomes, but had small effects for reductions in internalizing behaviors. Implications for intervening with preschoolers at risk of comorbid disruptive and anxiety behaviors are discussed. [This is the online version of an article published in "School Mental Health." For the final published version of this article, see EJ1229497.]