: Team-Based Learning (TBL), which is a student-centered instructional approach, has been applied in various health-related courses, but research on the effectiveness of TBL in radiologic technology is limited. More research is needed to examine the effectiveness of TBL within the field of radiologic technology as well as to study teachers' reflective practices for instructional development in TBL.: This study examines the effectiveness of TBL on students' learning and course instructors' instructional development during quality control activities in diagnostic imaging.: This study employed an action research approach with mixed-methods. The study was categorized using four TBL modules as the topics: film/screen receptors and processors, radiography, mammography, and computed tomography. Quantitative data included pre-test scores on individual readiness assurance tests (IRAT-pre), group readiness assurance tests (GRAT), and post-test scores on individual readiness assurance tests (IRAT-post). Qualitative data included students' responses to open-ended questions about their experience with TBL and transcripts of instructors' interviews.: Forty junior college students participated in the study. A non-parametric test was conducted to compare the scores. The results showed that the GRAT score was significantly higher than the IRAT-pre-score, and the IRAT-post score was significantly higher than the IRAT-pre-score. The IRAT-post score was significantly higher than the GRAT score for the first and fourth modules, but IRAT-post score was significantly lower than the GRAT score on the second and third modules. Using direct content analysis, five themes were coded around instructional development, while 15 themes were coded to understand students' experiences with TBL.: TBL can be an effective instructional approach to improve students' understanding of radiologic technology content. The results of this research can help instructors decide what action plan to implement to increase the effectiveness of TBL when further employing it for radiologic technology courses.