Objective: Classroom teachers can play an important role in supporting the implementation of a Comprehensive School Physical Activity Programme (CSPAP) by integrating physical activity (PA) into academic lessons, providing PA opportunities at recess and becoming role models for school-aged children. Grounded in the expectancy-value model, the goal of this study was to explore preservice classroom teachers' perspectives towards the programme in terms of their expectancy-related beliefs and subjective task values. Setting: A large public research university in the southwestern region of the USA. Method: Participants were 192 preservice classroom teachers (M[subscript age] = 19.85 years, SD = 0.6; female = 92%) enrolled in a public university. Participants responded to open-ended questions about their beliefs and values related to the CSPAP after learning about the programme model. Using thematic analysis, initial codes were generated from participants' responses, and three researchers who were knowledgeable in the CSPAP approach identified the final main themes. Results: The results revealed several overarching themes for understanding preservice classroom teachers' expectancy-related beliefs and subjective task values towards implementing CSPAP in schools, including the essential role of CSPAP in the family and community, innovation in pedagogy and the influence of the CSPAP on daily PA. Conclusion: Our study adds to the literature on preservice classroom teachers' beliefs and values towards the CSPAP using an expectancy-value model. Potential applications and suggestions for future practice are discussed.