This document attempts to provide managers and designers of information systems with a usable, practical "building block" system for unit costing. The model is sufficiently flexible to be applicable to a wide variety of cost control requirements; costing elements include project, product, account, organization and function. Design of the cost system involves knowledge of basic principles and the system reporting formats, product structure and counts, function roles, non-production costs and allocations. The next steps are identification of product lines, tagging cost elements and conducting trial runs. System implementation requires design parameters which reflect human limitations, controls, and staff education and orientation. In forecasting it is equally important to know what not to do as how to do it. The design and installation of the described cost system will produce fringe benefits which themselves almost justify the expenditures. Fourteen appendices provide working tools for system utilization. (AB)