A major task facing a number of different procuring agencies is the assessment of the developmental reliability of a product as contractors incrementally provide information. These agencies would like to use structured quantitative methodologies, as opposed to unstructured assessment currently adopted, to evaluate reliability throughout the life of a development programme as additional information becomes available. Due to resource constraints, any developed methodology must be cost and time efficient. This research attempts to develop a methodology for customers that is capable of assessing the information presented by a contractor in a reliability case to support decision making throughout the procurement process.