As reliability is one of the key factors in product quality, which is closely linked to customer satisfaction, the ability of companies to design products which will be "reliable" is key to their future market success. The paper presents a new design for reliability (DFR) method which assesses the suitability of mechanical system design configurations during the early stages of the design process. The method presented in this paper is a development of the work of Stephenson (1995) in which he sought to assess the reliability of technical mechanisms in large scale heavy plant equipment. The method described in this paper is based on three internal properties of technical systems, namely simplicity, clarity and unity proposed by Aguirre (1990). This paper, however, extends Stephenson’s approach by focusing on the definition of a more rigorous method for assigning clarity levels in design configurations. This is done by assessing clarity levels at the interfaces between one component and another, building a hierarchy of functions within a configuration, and lastly matching the properties of clarity and simplicity with each function hierarchy. The DFR method is illustrated in the paper with a case study example.