Despite growing recognition of the need for qualitative methods in health services research, there have been few attempts to define quality standards for assessing the results. This article acknowledges the desirability of a plurality of standards. However, it is argued that three interrelated criteria can be identified as the foundation of good qualitative health research: interpretation of subjective meaning, description of social context, and attention to lay knowledge. These criteria can be examined in relation to different dimensions of any research report, including theoretical basis, sampling strategy, scope of data collection, description of data collected, and concern with generalizability or typicality. But if the concern is with the appropriateness of care and with understanding the factors that shape lay and clinical behavior, then these criteria must form the basis of a hierarchy of qualitative research evidence.