Advanced practice registered nurses have assumed an increasing role as providers in the health care system, particularly for underserved populations. The aim of this systematic review was to answer the following question: Compared to other providers (physicians or teams without APRNs) are APRN patient outcomes of care similar? This systematic review of published literature between 1990 and 2008 on care provided by APRNs indicates patient outcomes of care provided by nurse practitioners and certified nurse midwives in collaboration with physicians are similar to and in some ways better than care provided by physicians alone for the populations and in the settings included. Use of clinical nurse specialists in acute care settings can reduce length of stay and cost of care for hospitalized patients. These results extend what is known about APRN outcomes from previous reviews by assessing all types of APRNs over a span of 18 years, using a systematic process with intentionally broad inclusion of outcomes, patient populations, and settings. The results indicate APRNs provide effective and high-quality patient care, have an important role in improving the quality of patient care in the United States, and could help to address concerns about whether care provided by APRNs can safely augment the physician supply to support reform efforts aimed at expanding access to care.