BACKGROUND AND OBJECTIVES: Family physicians frequently err when applying Current Procedural Terminology (CPT) evaluation and management (E&M) codes to their office visits, but there are few published prospective studies on educational interventions to improve coding. METHODS: Over a 6-year intervention period, 429 resident patient notes from return clinic visits were recoded by a faculty member with coding expertise. Feedback on coding accuracy and annual educational coding workshops were provided to the residents. Coding accuracy was calculated by subtracting residents' code from that of the faculty. Coding accuracy was analyzed cross-sectionally using all available data and longitudinally for 14 residents with data from all 3 years of the residency. RESULTS: Analysis of codings by 68 residents found that residents undercoded their clinic visits by 0.49 levels of service. Higher training year of the resident was associated with more accurate coding. Improvement over time was also found with the longitudinal analysis. However, comparison of 23 residents' coding from before the first feedback and didactic session to codings after starting feedback suggests that these improvements were not due to the intervention. CONCLUSIONS: Residents improved in coding accuracy over time, but our educational intervention may not have been responsible for the improvement.