The purpose of this current study was to examine the effect of a preschool teacher intervention around the use self-monitoring and the online learning modules. The interventions were delivered online using: online learning modules that provided exemplars of the operationally defined instructional language supports. The study included 12 Head Start classrooms, with 21 lead and assistant teachers who were randomly assigned to one of two treatment conditions: (a) graphed feedback based on self-reported data, or (b) written feedback based on performance data from videos. An experimental research design was conducted to evaluate the treatment effects for teachers and children (n = 107). The results suggested that regardless of condition, the majority of teachers increased their total frequency of language facilitation strategies. Additionally, the results suggest that teachers' receptive vocabulary skills and their role in the classroom (lead or assistant) may mediate the effect of the professional development intervention. (author abstract)