This column presents criteria for evaluation of nursing theories specified by Jacqueline Fawcett and Rosemarie Rizzo Parse. Fawcett's criteria are significance, internal consistency, parsimony, testability, empirical adequacy, and pragmatic adequacy. Some of those criteria are differentiated for grand theories and middle-range theories but are not differentiated by type of data-qualitative or quantitative-used to develop the theory. Parse's criteria are structure and process. Structure encompasses historical evolution, foundational elements, and relational statements. Process encompasses correspondence, coherence, and pragmatics. Parse's criteria are appropriate for the critical appraisal of all frameworks and theories, regardless of level of abstraction. Parse also presents a comparison of her own and Fawcett's criteria.