A working definition of nursing diagnosis was adopted by the North American Nursing Diagnosis Association (NANDA) Biennial Business Meeting in March 1990. Because of the working nature of the definition, members and nonmembers of the Association were invited to judge the merits and faults of the definition and to recommend areas needing further debate, analysis, or modification. The purpose of this article is to apply principles and rules of definition to an analysis of the working definition of nursing diagnosis as adopted by the NANDA General Assembly. In presenting this analysis, concerns and questions regarding the conceptual, logical, and grammatical clarity of essential elements (e.g., clinical judgment; individual, family, or community responses; actual or potential health problems; and actual or potential life processes) in the definition are posed; and, where appropriate, suggestions for clarification are offered. Further debate, research, and clinical testing is requested in an attempt to improve NANDA's very important contribution to the development of nursing practice theory.