As policy emerges from the interplay of economic, political, and social forces, determining whether research has made a difference to policy choices on aging issues is extremely difficult. Such a determination demands attention to the "black box" of the policy process, and the setting within which policy ultimately operates. This paper presents a Seniors' Independence Research Program as a case illustration of how research has made a difference to policy choices by stakeholder involvement throughout the research process. Strategies ensure stakeholder collaboration in policy issue search, filtration, definition, and prioritization; involvement in the design, implementation, and evaluation of health services models; and participation in achieving long-term evidence-based changes in policy and practice.