The Determinants of Implementation Behavior Questionnaire for school settings (DIBQ-S) was administered to examine questionnaire internal structure evidence and ascertain 127 Swedish school staff's perceived barriers to and facilitators of implementing the Inclusive Behavioral Support in Schools program. Using confirmatory factor analysis, we tested a 3-factor model (capability, opportunity, motivation) corresponding to the Theoretical Domain Framework and the COM-B system. Measurement of motivation was suboptimal, but a 2-factor model exclusively retaining capability and opportunity had fair fit. The questionnaire showed overall fair internal structure evidence. Facilitators related primarily to motivation, whereas potential barriers related to capability, opportunity, and motivation. Teachers working in early school years perceived higher opportunity and capability than teachers working in later school years. School staff in the implementation team perceived higher opportunity than other school staff. The DIBQ-S could support school implementations by ensuring that the process feels coherent, manageable, and meaningful for frontline implementers.