Information sharing among heterogeneou~ ~geusable agents in cooperative distributed search systems can greatly affect the quality of solutions and the runtime efficiency of the system. In this paper, we first give a formal description of shareable information in systems where agents have private knowledge and databases and where agents are specifically intended to be reusable. We then present experiments, run within a mechanical design system for steam condensers, that substantiate expected performance improvements related to information sharing and assimilation. Finally, we discuss the practical benefits and limitations of information sharing in application systems comprising heterogeneous reusable agents. Issues of pragmatic interest include determining what types of information can realistically be shared and when the costs of sharing outweigh the benefits.