Research on dynamic decision making in complex systems has paid little attention to the impact of interface design on human performance. Ecological interface design (EID) is a theoretical framework for designing computer interfaces for complex human-machine systems that addresses this issue. This article provides an overview of a research program on EID conducted in the author's laboratory. A detailed example showing how the principles of EID can be applied to design an interface for a simplified but representative thermal-hydraulic process-control simulation is presented. Also, the results from laboratory research, lessons learned from an industrial prototype, and the details of technology transfer to industry are reviewed. Collectively, the findings from this research program demonstrate that dynamic decision-making performance in complex systems can be significantly improved through appropriate interface design. This conclusion has significant implications for system dynamics research.