This paper describes afour-year experimental sof’ware reuse project conducted at Software Laboratories, Nippon Telegraph and Telephone. The targets of reuse are program code modules stored in a common library. The project is first described in detail; its framework, organizational structure, and activities are presented. The statistical results of the project are then shown. Some important aspects of software reuse are discussed, including impediments to software reuse, incentives and domain selection. Finally, it concludes that sof! ware reuse is inherently a managerial issue and that keyfactors for successful software reuse are senior management comtritment and good domain selection.