Abstract Background and Aims Continuing medical education (CME) aims at modeling best practice in promoting positive behavior. We hypothesized that participation in the case-based medical education “Challenging Cases of Glomerulonephritis: How Would You Diagnose and Manage These Patients?” would lead to improved knowledge and competence of nephrologists in the diagnosis and management of glomerulonephritis. Method The online CME activity consisted of 2 patient case scenarios, and it was delivered as an interactive, text-based format. Using a “test and teach” methodology to elicit cognitive dissonance, clinicians completed multiple-choice questions to test their application of evidence-based recommendations. Each response was followed by detailed, referenced, feedback to improve learners’ knowledge, competence, and confidence on the diagnosis and management of glomerulonephritis. The educational effect was assessed using a repeated-pairs design with pre-/post-assessment, where 3 multiple choice questions assessed knowledge/competence and 1 question assessed confidence. Significance was assessed using paired samples t-test for overall average number of correct responses and for confidence rating, and the McNemar's test for individual questions (5% significance level, P <0.05). Cohen's d estimated the effect size impact on number of correct responses (<.20 modest, .20-.49 small, .59-.79 moderate, ≥.80 large). Data were collected between July 15 2022 and September 27 2022. Results Comparison of responses to questions before and after education demonstrated a large educational effect for nephrologists (n = 119; d = 1.36; P <.001). Overall 84% nephrologists improved their knowledge/competence related to the diagnosis and management of glomerulonephritis (P< .001), showing a 76% relative increase in correct responses from pre- to post-CME (51% pre, 90% post). Significant increases in knowledge/competence on rare complement-mediated kidney diseases were reported (P <.001 for all comparisons) for: - Clinical manifestations (64% pre; 97% post) - Diagnosis (18% pre; 84% post) - Management (71% pre; 90% post) Around 55% of nephrologists showed a measureable confidence increase (P<.001) in their ability to recognize clinical information suggestive of rare complement-mediated kidney diseases. Conclusion This online, interactive, case-based CME activity significantly improved the ability of nephrologists to diagnose and manage patients with glomerulonephritis. Additional gaps were identified for future education.