The practices of schoolwide positive behavior support (SWPBS) are dependent on staff implementation in classroom and common areas throughout the school. Thus, gaining the support and commitment of school staff is a critical step toward reaching full implementation of SWPBS. However, achieving buildingwide support can be challenging; many schools fail to reach full implementation due to staff resistance. The Staff Perceptions of Behavior and Discipline (SPBD) survey was developed to help teams assess staff beliefs about behavior and discipline and their perceptions of schoolwide expectations, school climate, systemic supports, and resources. With a better understanding of staff perceptions and beliefs, teams can proactively address staff needs and concerns and build on existing capacities. The current study describes the development and explores the psychometric properties of the SPBD in a sample of 1,210 school staff from 36 schools. The results of exploratory factor analysis provide evidence of internal validity, and the results of hierarchical linear modeling analyses examine concurrent validity with key variables such as level of SWPBS implementation, staff knowledge, and training.