Socioeconomic status is a powerful determinant of health care outcomes. Affordability of health care probably has more effects on the treatment patients receive than do clinical factors or practitioner expertise. This article reviews and displays the research base for aspects of socioeconomic factors and measurement issues and their impact on outcomes. A strong and consistent relationship between socioeconomic factors and outcomes challenges nurses to find strategies for working effectively with vulnerable populations. The documentation of discrepancies in outcomes provides evidence of domains in which clinicians and policy makers can have measurable impact.