The lack of direction and sound empirical evidence to support the use of high fidelity simulation in nursing education has been attributed to the lack theoretically based models that can be used to structure the use of educational simulation. This paper proposes a theoretically-based model called the Knowledge, Action and Reflection (KAR) model that can be used to structure high fidelity simulations. Theories from nursing, education and cognitive psychology were reviewed and synthesized into a comprehensive model that is designed to help educators design, implement, and evaluate high fidelity simulation scenarios for nursing education. The use of a theoretically defined model provides a testable framework to build evidence necessary to identify best practices for educational simulation.<br />