Accordingly, the overarching goal of this project is to provide a better understanding of actual teacher BMP and their relations to children’s outcomes in the context of Head Start. The process of achieving this goal will occur across three distinct but related studies, each aligned with one of the following aims and their corresponding research questions: Aim 1: To gather Head Start teachers’ perspectives on their BMP and process. RQ1. What BMP do teachers report using in their classrooms? RQ2. Why do teachers find certain BMP effective for addressing challenging behavior? RQ3. How and when do teachers decide to use specific BMP in their classrooms? RQ4. What resources and supports do teachers find most useful for learning and actualizing BMP in classrooms? Aim 2: To characterize the day-to-day BMP of Head Start teachers in their classrooms using classroom observations and teacher interviews. RQ4. What, with what kind of frequency, and under what conditions are the observed BMP used in Head Start classrooms? RQ5. What are teachers’ perspectives on the observed characterization of their BMP? Aim 3: To develop a BMP measure and determine whether measured practices are associated with children’s challenging behavior and social-emotional skills. RQ6. To what extent are teachers’ BMP associated with children’s challenging behavior and social-emotional skills across the Head Start year? RQ7. Do initial challenging behaviors moderate the associations between BMP and children’s challenging behavior and social-emotional skills across the Head Start year? To address these aims, the current project will use multiple methods with data drawn from teachers in local Head Start centers and previously recorded videos of Head Start classrooms. (author abstract)