Hurricane Katrina was one of the worst natural disasters in U.S. history. The effects of the hurricane were particularly devastating in the city of New Orleans. Most of the damage was due to the failure of the levee system that surrounds the city to protect it from flooding. This paper presents the results of centrifuge models conducted at Rensselaer Polytechnic Institute and the U.S. Army Corps of Engineers simulating the behavior of the levees at London Avenue North and South that failed during Hurricane Katrina. Those levees failed without being overtopped by the storm surge. Also included are the results of a centrifuge model of one levee section at Orleans Canal South, which did not fail during the hurricane. The key factor of the failure mechanism of the London Avenue levees was the formation of a gap between the flooded side of the levee and the sheetpile. This gap triggered a reduction of the strength at the foundation of the protected side of the levee. The results are fully consistent with field observations. Gulf of Mexico, and the Mississippi River running through the southern portion of New Orleans. The levee system that surrounds the city protecting it from flooding experienced extensive damage during the hurricane, leaving roughly 80% of the city under water. Shortly after the hurricane, several multidisciplinary groups were formed with the goal to understand the causes of this disas- ter, in particular, the failure of the levee system. Many of those independent investigators visited New Orleans shortly after the hurricane to capture as much data and field observations as pos- sible before the levee failure sites were disturbed by ongoing emergency repair activities. The field observations described in this paper were taken from a report published about three months after Katrina and sponsored by the National Science Foundation Seed et al. 2005. All of the work reported in this paper was conducted as part of the evaluation performed by the U.S. Army Corps of Engineers USACE regarding the hurricane protection system in southeast Louisiana. That effort initiated by the Chief of Engineers for USACE was termed the Interagency Performance Evaluation Taskforce IPET. Part of that effort was a thorough analysis of the performance of the hurricane protection system. A component of that work was physical modeling of selected locations of the levee system, which is presented herein. The USACE provided critical information for the research presented in this paper, such as the pre-Katrina geometry of the levees and material properties, as well as storm surge water elevations and the general progres- sion of events during Katrina, which was later published in USACE 2006. This paper presents the results of 50g centrifuge physical mod- els of the performance of two levee sections at London Avenue and one levee section at Orleans Canal. The tests were conducted at the Rensselaer Polytechnic Institute RPI in Troy, N.Y., and the USACE, Engineer Research and Development Center ERDC in Vicksburg, Miss. Duplicate physical models of the levees reported in this paper were conducted at both facilities to