Effective interprofessional collaborative practice (IPCP) requires not only collaboration competencies but also strong professional and interprofessional identities, which require personal, professional, and interprofessional reflection. No instrument is available to assess students’ reflection abilities covering their personal, professional and interprofessional identities. Therefore, this study developed a student self-reflection questionnaire in the interprofessional education (IPE) context. This study used an exploratory sequential mixed-methods approach, which began with a scoping review and focus groups (FGs) with 122 respondents, followed by an expert review, cognitive interviews (involving 14 fourth-year students), and a pilot study (involving 52 fourth-year students). The last step was validation using the exploratory factor analysis (EFA) method involving 630 seventh-semester students from medical and health professions. The scoping review and FGs suggested 92 items that were reviewed by eight experts and resulted in 64 relevant items. Fifty-three items were selected through cognitive interviews, and 50 items resulted from the pilot study. A total of 50 items were analysed with EFA and resulted in three factors: (a) self-awareness and the development of interprofessional collaborative teams (22 items, Cronbach alpha: 0.946); (b) openness/readiness and efforts for adaptation in interprofessional collaborative teams (14 items, Cronbach alpha: 0.938); and (c) reliability and interaction in interprofessional collaborative teams (14 items, Cronbach alpha: 0.824). Each factor contained personal, professional, and interprofessional aspects. This study resulted in a valid and reliable instrument for assessing students’ self-reflection abilities in IPE and exploring students’ IPE self-reflection in the personal, professional and interprofessional aspects to support identity formation and interprofessional collaboration. © Malaysian Association of Education in Medicine and Health Sciences and Penerbit Universiti Sains Malaysia. 2024.