This action research case study was intended to qualitatively determine how system thinking and system dynamics modeling informed regional strategic planning and to derive a grounded theory based upon data collected during the Steinbeck Innovation Cluster strategic planning process. Three areas of previous research were investigated: systems, complexity, networks and system dynamics; strategic planning; and industrial clusters. The grounded theory that emerged from my research is that: System thinking and the use of small, system dynamics models can enhance the awareness of decision and policy makers by clarifying dynamic complexity and structure/behavior relationships and may contribute to collaborative, cross-sectoral effort that diminishes the pitfalls of policy resistance in regional strategic planning. This study contributes to each of the three areas of research already mentioned by addressing perceived gaps at the intersection of systems theory, theories of sustainable cluster development, and theories of strategic planning. Furthermore, this study builds upon previous attempts to evaluate the impact of system dynamics modeling on mental models by qualitatively evaluating pre and post-intervention responses of actual regional strategic planners from three organizational cross-sectors that included the private sector, the non-profit sector, and the government or civic sector.