OBJECTIVES: The aim of the study was to evaluate an educational intervention targeting the acquisition and retention of critical core skills of defibrillation in first-year pediatric residents using simulation-based training and deliberate practice. METHODS: From January 2011 to April 2012, a total of 23 first-year pediatric residents participated in a pretest-posttest study. An initial survey evaluated previous experience, training, and comfort. The scoring tool was designed and validated using a standard setting procedure and 60% was determined to be the minimum passing score. The 1-hour educational intervention included a brief video describing the defibrillator, 10 to 15 minutes of hands-on time with the defibrillator, and 30 minutes of simulation-based scenarios using deliberate practice with real-time feedback. RESULTS: The number of subjects who achieved competency in defibrillation skills increased from 8 to 16 of 23 (35% vs 70%, P < 0.05), pretest versus posttest, with the posttest occurring 4 months after the intervention. There was a significant improvement in checklist score (53% vs 68%, P < 0.05) and time to defibrillation (282-189 s, P < 0.05). For those who initiated chest compressions, there was a nonsignificant improvement in time to compressions (50 vs 33 s, P = 0.08). Previous Pediatric Advanced Life Support training was not associated with performance on pretest or posttest. CONCLUSIONS: This brief educational intervention was shown to be effective 4 months after instruction in achieving and retaining competency of defibrillation skills by first-year pediatric residents. In the process, we uncovered educational gaps in cardiopulmonary resuscitation and other resuscitation skills that need to be addressed in future educational interventions and training.