The purpose of this study was to identify and examine how schools implementing schoolwide positive behavioral interventions and supports (PBIS) were engaging families in their Tier I PBIS systems. In addition, reported implementation of practices and the availability of resources were examined in relation to fidelity of PBIS implementation. Participants included PBIS Leadership team representatives from 302 schools across three states. Findings revealed the most common ways in which schools (a) communicated with families about their PBIS systems, (b) worked with families to support PBIS at school, (c) supported family use of PBIS at home, and (d) built partnerships to support PBIS. Finally, communicating with families about PBIS and supporting families to help their child follow school expectations were related to fidelity of PBIS implementation. Implications and future research directions are discussed.