Aim/Purpose: These days educators are expected to integrate technological tools into classes. Although they acquire relevant skills, they are often reluctant to use these tools. Background: We incorporated online forums for generating a Community of Inquiry (CoI) in a faculty development program. Extending the Technology, Pedagogy, and Content Knowledge (TPACK) model with Assessment Knowledge and content analysis of forum discourse and reflection after each CoI, we offer the Diagnostic Tool for Learning, Assessment, and Research (DTLAR). Methodology: This study spanned over two cycles of a development program for medical faculty. Contribution: This study demonstrates how the DTLAR supports in-depth examination of the benefits and challenges of using CoIs for learning and teaching. Findings: Before the program, participants had little experience with, and were reluctant to use, CoIs in classes. At the program completion, many were willing to adopt CoIs and appreciated this method's contribution. Both CoIs discourse and reflections included positive attitudes regarding cognitive and teacher awareness categories. However, negative attitudes regarding affective aspects and time-consuming aspects of CoIs were exposed. Participants who experienced facilitating a CoI gained additional insights into its usefulness. Recommendations for Practitioners: The DTLAR allows analyzing adaption of online forums for learning and teaching. Recommendation for Researchers: The DTLAR allows analyzing factors that affect the acceptance of online fo-rums for learning and teaching. Impact on Society: While the tool was implemented in the context of medical education, it can be readily applied in other adult learning programs. Future Research: The study includes several design aspects that probably affected the improvement and challenges we found. Future research is called for providing guidelines for identifying boundary conditions and potential for further improvement.