Implementing anti-bullying programs or program components in schools is a complex process affected by personal, organizational, and system factors. Therefore, it is important to understand factors that may affect the implementation process to understand why the effectiveness of different programs or program components may vary. The chapter focuses on the challenges and the lessons that can be learned from implementing tailored bullying prevention components in schools based on a whole-community approach in Sweden. The challenges discussed relate to three types of challenges—lack of resources, the necessity for the initiative to be well anchored, and resistance to change—that affected the outcomes of the project. The results also show that the ways in which the challenges were dealt with affected the outcomes and that the challenges are closely related to each other and must be dealt with taking into account the schools’ unique contextual conditions.