Nurses have a social responsibility to evaluate the effect of nursing practice on patient outcomes in the areas of health promotion; injury and illness prevention; and alleviation of suffering. Quality assessment initiatives are hindered by the paucity of available data related to nursing processes and patient outcomes across these three domains of practice. Direct care nurses are integral to self-regulation for the discipline as they are the best source of information about nursing practice and patient outcomes. Evidence supports the assumption that nurses do contribute to prevention of adverse events but there is insufficient evidence to explain how nurses contribute to these and/or other patient outcomes. The purposes of this article are to examine the imperatives, ideal conditions, history, and challenges related to effective outcome measurement in nursing. The article concludes with recommendations for action to move quality assessment forward, such as substantial investment to support adequate documentation of nursing practice and patient outcomes.