Due to the unique features of early childhood classrooms, teachers routinely modify the social and physical environment to support children with mild to moderate challenges. Yet despite their access to behavioral consultants, school-based prekindergarten programs are more likely to expel young children from their classroom settings compared with expulsion rates of students with behavior problems in K-12th grades. The frequency of expulsion is disconcerting because it signals that programs are unprepared and unable to successfully ameliorate the needs of young children with challenging behavior. As problem behavior persists, children are at an increased risk for peer rejection and school Failure. Functional Behavioral Assessment (FBA) and function-based interventions have been recognized as effective practices for identifying and treating problem behavior in early childhood environments. Function-based interventions are unique in that they are used to address the function of a challenging behavior (i.e., why the challenging behavior occurs) instead of addressing the form of the challenging behavior (i.e., what the challenging behavior looks like). To develop a function-based intervention, an FBA is conducted to identify why the behavior occurs. The purpose of this article is to provide examples and a step-by-step description of an effective and practical approach for conducting an FBA and developing function-based interventions using the "Decision Model" developed by Umbreit, John, et al., "Functional Behavioral Assessment and Function-based Intervention: An Effective, Practical Approach" (2007). In summary, the procedures described in this article provide a systematic approach for connecting data collected during the FBA to intervention components. FBA and the use of the "Decision Model" are effective procedures for identifying the function of target behaviors and developing function-based interventions. Through the use of the methods described in this article, teachers can further support young children with challenging behavior and promote positive behavior change in their classrooms.