Background: The Incredible Years® (IY) Teacher Classroom Management (TCM) programme may reduce disruptive behaviour in the classroom and improve child and teacher mental health; however, few studies have considered how acceptable TCM is to teachers or what facilitators and barriers there are to its implementation. Aims: In this paper we examine the acceptability of the full 6-day TCM programme and teachers' perceived barriers and facilitators to implementation in the English (UK) primary school context. Sample: Forty-four English (UK) primary school teachers who attended the TCM programme as part of the STARS trial. Methods: We completed focus groups and telephone interviews with participating teachers 2 months after they completed the TCM programme. Thematic analysis was used to examine the data, and a framework approach was applied to organize and summarize themes. Results: Teachers liked the structure of the course, the peer group learning environment, delivery methods, and the opportunity to reflect outside the classroom on their practice. They reported that the video clips used lacked cultural relevance and highlighted the importance of group leadership style. Perceived facilitators to implementation included an understanding of the theory underpinning TCM and adaptability of the TCM strategies. Barriers included perceived gaps in the course content in relation to challenging behaviour, applying strategies with older children and the school context within which teachers were working. Conclusion: Our findings suggest high levels of acceptability to TCM overall, but also highlight the need for a whole school approach to combat potential barriers to implementation.