OBJECTIVE: The Accreditation Council for Graduate Medical Education and the Liaison Committee on Medical Education have mandated the transition from written global evaluation methods to competency-based assessments in resident and medical student training. Assessment of competency requires analysis of performance data from numerous sources. This article reviews characteristics of Web-based evaluation and assessment systems and recommends areas for further development. METHOD: The authors review functions common to a variety of online evaluation and curriculum management systems with attention to their adaptation for competency documentation and assessment. Details of online global assessments, examination methods, electronic portfolios, procedure/case logs, and survey systems are provided along with a list of Internet resources. RESULTS: Online evaluation and assessment systems not only provide data on trainee competence but can provide valuable feedback on faculty teaching, curriculum quality, and the learning environment. Suggestions for future development, legal ambiguities that could become obstacles, and the need to clarify the responsibility for funding this work are discussed. Web-based performance assessment and evaluation are seen in the larger context of moving toward competency assessment of practicing physicians. CONCLUSIONS: Online assessment systems offer advantages over paper systems in allowing robust data analysis, reporting, and flexibility. A national online procedure/case log tracking system would facilitate gathering data that could provide one type of experiential benchmark for determining competency.