One objective in Finnish basic education is for pupils with disabilities or behavioral problems to be able to participate in mainstream education and ordinary classrooms. Positive behavior support (PBS) is an approach that offers multi-tiered behavior support for pupils. In addition to providing support at a universal level, educators need to have the necessary skills to provide more intensive individual support for pupils who need it. Check-in/Check-out (CICO) is a research-based individual support system that is widely used in PBS schools. The Finnish application of CICO includes an individual behavior assessment process for pupils with persistent challenging behaviors. In this article, we examined which pupils in Finnish PBS schools are provided CICO support, and in particular, how many have identified needs for specific pedagogical support or behavior-related disabilities, and whether educators find CICO to be an acceptable way of supporting behavior in an inclusive school setting. CICO support was found to be used the most in the first four grade levels, and support was offered mainly for boys. The number of pupils receiving CICO support in participating schools was much lower than expected, and CICO seemed to be secondary to other pedagogical supports. The social validity of CICO was equally high for all grade levels and pupil groups. The experienced effectiveness was somewhat lower among pupils with a need for pedagogical support in basic academic skills. The results suggest that Finnish schools may have a high threshold for starting structured behavior support despite its high acceptability. Implications for teacher education and the development of the Finnish version of CICO are discussed.