The Frangible Abdomen is a crushable Styrofoam insert for the abdominal region of the Hybrid III family of dummies, which has biofidelity, and assesses the occurrence of submarining and its risk of injury. It was first developed for the mid-sized male Hybrid III dummy. This paper describes the design of the Frangible Abdomen for the small female Hybrid III dummy, and how to use it to assess the occurrence and the risk of injury from submarining.The force-deflection properties of the mid-sized male insert were scaled to the small female dimension using equal stress/equal velocity scaling. Sled tests were run to compare the kinematic and dynamic performance of the baseline small female Hybrid III dummy with the same dummy modified to incorporate the Frangible Abdomen. The kinematic and submarining performance of the small female Hybrid III dummy was unchanged by the addition of the Frangible Abdomen.The Frangible Abdomen was easy to install and use, and had excellent repeatability. Injury assessment with the Frangible Abdomen is based on the depth of foam deformation. Tables and graphs are included which relate the risk of injury to the amount of crush. Issues regarding its use, handling, applicability, spinal injury, belt roping, and unilateral submarining are discussed. Appendices containing information on retrofitting existing dummies, calibration testing of Styrofoam, and with more detailed tabulations of sled test data are provided.