This workshop was the second of a series of four SCEC5 workshops designed to evaluate the importance of each of the four ingredients required for dynamic earthquake rupture simulations. The four ingredients are: initial stress conditions, fault geometry, rock properties, and fault friction (Figure 1). This workshop included a range of views of how fault friction operates in the Earth, based on information from lab experiments, from field observations, and from dynamic rupture simulations. The participants also learned about two current related SCEC projects: the dynamic rupture code validation project and the surface fault displacement project.