Too often, when information systems development projects are completed and delivered, the systems are put on the shelf and never used. Maybe this was acceptable in the past, however, with the reduction in defense-related contracts and shift towards the more competitive commercial market, it is imperative that information systems development organizations deliver systems that meet the needs and expectations of the customer to ensure their future survival. This paper presents an integrated approach to solving this problem by providing a formal, comprehensive method of establishing and validating quantitative system requirements. Described in detail, is a tool called INFOSYM, which not only facilitates the system requirements definition process, but also provides a standard method of recording and tracking a majority of the data required for systems design and development. Organizations can build a repository of this data for all systems development projects to establish a library of reuse data and to estimate costs and resources of future projects more accurately.