Over the past 30 years, health status assessment methods for adults have proliferated. Numerous generic, disease-specific, and preference-based measures now exist that tap diverse aspects of functioning, well-being, symptom states, and subjective perceptions of health. The evolution of the state of the art in adult health status assessment is reviewed. Applications of these tools in health services research, health policy, and clinical practice are discussed. Recommendations are offered for selecting among the armamentaria of tools. Conceptual and methodological challenges that confront instrument users and developers alike are identified and discussed.