Low staff support for schoolwide positive behavior interventions and supports (SWPBIS) is a barrier to implementation and sustainability. In this qualitative study, we identify staff opposed to SWPBIS among staff in 36 schools across 9 districts in western Washington. Nonsupportive staff (n = 44) are compared to supportive staff (n = 1,166) on demographic variables. Then, open-ended statements provided by nonsupportive staff are coded and analyzed to identify themes and develop an understanding of concerns about the SWPBIS initiative in their schools. Nonsupportive staff were concerned for the commitment and participation of all stakeholders, including staff, administrators, and students. Some sources of opposition were attributable to misunderstandings of SWPBIS and outright philosophical disagreements. Other sources of staff opposition were attributable not to the SWPBIS framework, but to school-level factors such as negative climate. We provide consultants with suggestions for engaging nonsupportive staff as well as directions for future research.