Securing long-lasting positive intergroup relations is of high priority in the multi-cultural European Union. Developing and promoting integration within the school context is a matter of interest to both researchers and practitioners. This study investigated the effects of a mastery-oriented motivational climate intervention using the TARGET framework on students’ psychological integration (identification with, and inclusion in physical education [PE] class), in culturally diverse school classes. The intervention was conducted using a quasi-experimental design in 7th to 9th graders over 18 weeks. Two school classes were assigned to an intervention group (n = 38) and three school classes received regular PE instruction. The intervention group was compared with a control group (n = 56). Results indicated a positive effect of the intervention on students’ feelings of inclusion in PE class in the intervention condition compared to the control condition. Mediation analysis revealed that this effect operated through decreased performance climate perceptions. Our findings suggest that such an intervention using the TARGET framework may affect students’ feelings of inclusion within the PE class through differences in performance climate perceptions. Findings highlight the importance of perceived motivational climate in PE for students’ psychological integration in culturally diverse PE settings and suggest the effectiveness of a motivational climate intervention. © 2021 International Society of Sport Psychology.