On the basis of the implementation of Schoolwide Positive Behavior Supports in high schools, the present study examined the effect of supporting buy-in through conducting needs assessments and focused professional development for high school staff when implementing Schoolwide Positive Behavior Supports. The effectiveness of the 2 additional items was investigated using 2 treatment schools and 2 comparison schools. The hypothesis was that schools with enhanced support would implement Schoolwide Positive Behavior Supports better and student office discipline referrals would drop as a result of the better implementation. Overall, the results showed the treatment schools improved in fidelity and demonstrated significant improvement in numbers of office discipline referrals. In contrast, both comparison schools decreased in fidelity, and none demonstrated significant changes in office discipline referrals. Suggestions for practice and future research are provided.