To date, data-based research has not been conducted specifically on the use of systems of schoolwide positive behavioral support (SW-PBS) in early childhood settings; however, several articles have described how the process can be implemented to support children in early childhood settings. Research has also documented early childhood teachers' support of the importance of using behavior support strategies. SW-PBS is more commonly referred to as program-wide PBS (PW-PBS) in early childhood education because the "classrooms" are often spread out over several settings. There are also differences in the application of key features of PBS in early childhood programs. Given the unique characteristics of preschool settings, it is clear that more research is needed in the area of utilizing systems of PW-PBS in all preschool early childhood programs and particularly in those that serve children at risk for behavior problems (e.g., Head Start). The need for more support in the area of working with challenging behavior has been acknowledged by Head Start administrators and staff. Head Start teachers have reported that 40% of their students exhibited one or more problematic behaviors on a daily basis and many students exhibited six or more each day. Overall, children in Head Start classrooms are at increased risk for problem behavior, and teachers in Head Start classrooms are often not adequately prepared to manage behavior problems. Therefore, more research is needed to explore interventions that Head Start teachers use to support appropriate behavior in their classrooms. This study explores the implementation of specific features of PW-PBS in three Head Start centers over the course of one year. Positive teacher behaviors that were targeted included precorrection and praise. Data were also collected on reprimands, redirection, and nonspecific praise to determine if those behaviors decreased as teachers began to use more proactive and positive approaches to managing behavior. Teacher behavior before and after different phases of professional development in the PBS process was monitored. This type of data can inform professionals of implementation at a system-wide level and direct any subsequent needs for professional development. (Contains 1 table.)