Development of a multicomponent mental health consultation program for a countywide Head Start program is described. The consultation program incorporates strategies from the evidence-based practice, Teacher-Child Interaction Training (TCIT). Through large group professional development trainings before the school year, comprehensive feedback reports based on observations, and in-class coaching via modeling and performance feedback on teachers' use of TCIT skills, the consultation program served 55 Head Start classrooms with 789 children. Outcome data are presented on teachers' improvement in TCIT skill use and the relative effectiveness of two coaching methods (i.e., modeling and performance feedback) used during consultation. Results from multilevel modeling analyses indicated that teachers improved in the use of multiple observed TCIT skills between the initial and midyear assessment (i.e., increased frequency of labeled praises, reflections, behavioral descriptions, and commands that were complied with; decreased frequency of commands that children did not have an opportunity to comply with). Additionally, teachers who received coaching in the form of performance feedback, in comparison to modeling, exhibited greater gains in the frequency of labeled praises and commands that resulted in compliance. Discussion focuses on implementation of evidence-based practice in large-scale preventative early interventions, study limitations, and directions for future research.