Head Start teachers and their aides (n = 23) were randomly assigned to either the experimental or active control group in this exploratory study of the effectiveness of child–teacher relationship training (CTRT) on 20 economically disadvantaged children exhibiting disruptive behavior. CTRT is based on the principles and procedures of child–parent relationship training (CPRT), a 10-session play based model, which uses parents and caregivers as therapeutic agents of change. Analysis of pre- to mid- to posttests results revealed that, when compared to the active control group, CTRT demonstrated a large treatment effect on reducing children’s levels of disruptive behavior. The statistical, practical, and clinical findings of this study provide validation of CTRT as a viable early mental health intervention for preschool children in Head Start exhibiting disruptive behaviors. (PsycINFO Database Record (c) 2018 APA, all rights reserved)