I almost feel like it's the same with any other learning skill - math, reading, writing - you simply have to keep teaching, keep modeling, and doing it consistently from the time they enter your doors till the time they graduate. I am a school counselor and have used a few different programs, including working in a school that was very consistent with PBIS. As another poster said, when kids are coming in from homes filled with chaos/trauma, it is a hard thing for students to practice. My current school uses the "Too Good" program...not sure if it's really any different/better than anything else, but it has a good message and lessons that build on the last. However, I still see kids nod their heads and participate in the program, and then go back to being spiteful with each other. It's a process!