Military leaders at many levels have used strategic planning in various ways to position their organizations to respond to the demands of the current situation, while simultaneously preparing to meet future challenges. This Letort Paper examines how the different Chairmen of the Joint Chiefs of Staff from 1990 to 2012 used a strategic planning system to enable them to meet their formal leadership responsibilities as outlined in Title 10 U.S. Code. As such, it provides an historic perspective in assessing the different Chairmen's leadership legacies in using and modifying their strategic planning system. It also has a contemporary focus as it describes the planning system's current processes and products. Because the strategic environment and its challenges can affect both a leader and staff's use of a planning system, this Paper examines major characteristics of the current strategic environment during this 2-decade-plus time frame. The current decade's challenges, which began in 2010 and are still evolving, appear to be significantly different from those of the previous decade in light of the nation's fiscal challenges, the military's departure from Iraq, and forecasted future force reductions in Afghanistan. The current decade's challenges associated with shifting, interest-driven conditions, and a multi-nodal world as described in the 2011 National Military Strategy are different from the rigid security competition between opposing blocks associated with the 1990s. To respond to these challenges, the planning system was formally revised five different times during this period. The most current revision in 2008 has specified processes and planning products under an overall framework of assess, advise, direct, and execute components. The assess component provides a comprehensive joint assessment of global challenges and joint capabilities, as well as force readiness and risk concerns. The advise component has specific resource, risk, and strategic assessment products to enable the Chairman to execute roles associated with being the principal military advisor, articulating combatant commander concerns, validating military requirements, and providing advice in other strategic documents. The direct component focuses on implementing the President and Secretary of Defense's guidance through strategies, plans, and doctrine. Finally, the execute component focuses on assisting with the command function through the National Military Command Center associated with planning and execution of orders. An examination of how the seven Chairmen used this planning system provides a formal leadership legacy and, most importantly, five broad decision making insights for future senior leaders. First, leaders need to articulate a vision to shape effectively any long-term change. Second, leaders need to ensure their planning system maintains a balance between flexibility and structure. Third, the strategic planning process needs to be inclusive and integrated with processes of leaders whose level of authority is above and below the Chairman. Fourth, leaders must modify the planning system to align with their decision making style and organizational challenges. Finally, a strategic planning system that has well-defined and inclusive processes and products can be a powerful mechanism to create a climate and help embed a culture.