Background: In order to develop Stepped Care trauma-focused cognitive behavioral therapy (TF-CBT), a definition of early response/non-response is needed to guide decisions about the need for subsequent treatment. Objective: The purpose of this article is to (1) establish criterion for defining an early indicator of response/non-response to the first step within Stepped Care TF-CBT, and (2) to explore the preliminary clinical utility of the early response/non-response criterion. Method: Data from two studies were used: (1) treatment outcome data from a clinical trial in which 17 young children (ages 3-6 years) received therapist-directed CBT for children with posttraumatic stress symptoms (PTSS) were examined to empirically establish the number of PTSS to define early treatment response/non-response; and (2) three case examples with young children in Stepped Care TF-CBT were used to explore the utility of the treatment response criterion. Results: For defining the responder status criterion, an algorithm of either three or fewer PTSS on a clinician-rated measure or being below the clinical cutoff score on a parent-rated measure of childhood PTSS, and being rated as improved, much improved or free of symptoms functioned well for determining whether or not to step up to more intensive treatment. Case examples demonstrated how the criterion were used to guide subsequent treatment, and that responder status criterion after Step One may or may not be aligned with parent preference. Conclusion: Although further investigation is needed, the responder status criterion for young children used after Step One of Stepped Care TF-CBT appears promising.