Abstract: Development of bespoke design methodologies to make them recognizable to designers working in a specific engineering domain is a requirement to making them more acceptable. Application of domain-specific design methodologies by industry will promote the adoption of systematic design, bringing with it the inherent advantages of adopting a systematic approach. This paper examines the development of a domain-specific methodology for fluid power systems, a specialist design discipline within mechanical engineering, and describes the implementation of the methodology within a computerized design support tool. Key technical and methodological features of the design tool are described with specific reference to the knowledge capture and representation processes employed. As such, the need for design theory to be adapted to meet the needs of specific engineering domains within industry is demonstrated.