Identification and measurement of the outcomes of nursing care have received great attention in the past decade. With advances in information technology, large clinical data bases are being developed for use in outcomes evaluation. It is important that nurses be thoughtful in designing the data elements that will be included in these data bases. Key data elements include nursing diagnoses, interventions, and nursing sensitive outcomes. Multiple variables influence the outcome of health care. It is important in evaluation that system, patient, and provided characteristics be considered, especially when developing benchmarks for comparison of outcome achievement. Data related to the process of care are needed beyond provider encounter, and nurses must be cautious that the care they give is not credited to other providers. Longitudinal clinical data bases that contain key variables related to the delivery of nursing care can yield valuable knowledge on the best methods to measure and interpret the contribution of nursing care to the health of the nation.