Implementation of management science via situational normativism, a descriptive-normative approach to decision making, is discussed. The situational normativism process involves a search by manager and management scientist for a synthesized situational frame of understanding (involving analytic and heuristic knowledge, as discussed in the paper) within which solutions to the decision situation problem can be found. Implementation constraints (e.g., cognitive style constraints and political constraints) are explicitly considered. A situational normativism organization development concept is suggested. Mutual understanding between scientist and manager evolves from and is fed to the situational normativism search process. Unity of science and management, implementation, and organization (system) development—in the sense of attaining evolved-in-the-process goals—are viewed as natural corollaries of working towards a synthesized situational frame of understanding via situational normativism. Some examples illustrating aspects of the organization development concept arising from practice are presented.