This paper describes the development of a decision support tool, an adoption assessment matrix based on critical adoption factors, that addresses a need in industry; namely, to improve the overall understanding of the constituent parts of agile systems development methodologies. It highlights the importance of critical adoption factors to the adoption of an agile method and illustrates the usefulness of a decision support process to determine the viability of an agile method for a specific software project. The paper describes the results of a series of workshops (two carried out in commercial software developement companies, and one with personnel from the British Minsitry of Defence) where the adoption assessment matrix was used to assess the suitability of agile methods in software development projects. A major benefit of the tool is that it guides discussion, concentrating the debate on the critical factors, applied to the individual project. These discussions proved to be as valuable as the output of the tool itself. The results of these workshops show that an argument can be made for the use of and benefit of such a decision support process in industry, in supporting the decision to adopt an agile methodology.