The period foregrounded participatory group model building as a core SD methodology, enabling stakeholder engagement, shared mental models, and consensual problem framing in complex socio-technical systems. System dynamics also adopted a learning-environment framing with dynamic simulations acting as learning tools and policy exploration environments, helping illuminate learning loops, policy resistance, and tradeoffs. Hybrid modeling approaches gained prominence, integrating system dynamics with agent-based and discrete-event methods to study complex supply chains and software processes, fostering cross-method insights. Strategic management and organizational change patterns showed SD informing planning, risk assessment, and change processes in engineering and business contexts. Theory, cognition, and education in SD—pattern recognition, public participation, and knowledge transfer—were advanced through critiques, pattern-oriented modeling, and systems thinking inventories. Historical Significance: The period solidified participatory, learning-centered, and hybrid SD practices, expanding the role of SD in education, consulting, and organizational design. It catalyzed the adoption of group model building scripts, flight-simulator style policy experiments, and thinking inventories as standard methodological tools, shaping how practitioners approach complexity and policy through systems thinking.