The IOM report, To Err is Human, Building a Better Health System, galvanized public and political attention to the prevalence of medical errors in the Unites States. The IOM set a clear goal, “given the current knowledge about the magnitude of the problem, the committee believes it would be irresponsible to expect anything less than a 50 percent reduction over five years.” As part of the IOM's four-part strategy was a recommendation that error reporting systems be established. No one denies that errors that occur in medicine can not be reduced if they cannot be defined. To achieve this goal of reducing errors, we have established a definition of a “medical error”, described the current taxonomies that have been created over the last five years for their classification, and suggested a conceptual model for designing and testing a medical error reporting system. A system that facilitates identification, relies on health professionals and electronic repositories of clinical information to report events, and tracks and monitors medical errors, reliably, efficiently, and accurately is the objective of our design. Our next step is to implement, test, and evaluate this system based on our research.