In nursing science, concept development is a necessary prerequisite for meaningful basic research. Rodgers' evolutionary concept analysis is a method for developing knowledge in nursing science. The purpose of this article is to present Rodgers' evolutionary concept analysis as a valid scientific method. A brief description of the evolutionary process, from data collection to data analysis, with the concepts' context, surrogate and related terms, antecedents, attributes, examples and consequences, is presented. The phases used in evolutionary concept analysis are illustrated with eight actual studies (1999-2009) from nursing research. The strength of the method is that it is systematic, with a focus on clear-cut phases during the analysis process, and that it can contribute to clarifying, describing and explaining concepts central to nursing science by analysing how a chosen concept has been used both within the discipline itself and other health sciences. While an interdisciplinary perspective which stresses the similarities and dissimilarities of how a concept is used in various disciplines can increase knowledge of a concept, it is important to clarify the specific with the discipline. Nursing research should focus on the unambiguous use of concepts, for which Rodgers' method constitutes a possible method. The importance of using quality criteria to determine the inclusion of material should, however, be emphasised in the continued development of the method.