The single fiber fragmentation test has been modified by embedding multiple fibers into matrix resin. During testing, we examined the interfacial shear strengths between the fibers and the matrix. In addition, the time-dependent nature of the fragmentation process was considered. In the fragmentation test, we examined the failure process of two fibers placed far from each other, and we found that the failure profile of the two fibers were similar to the failure profiles from tests done on single fibers. When we examined three fibers, we found that the measured interfacial shear strength values were much greater than the shear strength values from either the single or two fiber tests. However, when we used three fibers, we found it difficult to control the interfiber spacing. Consequently, whenever the interfiber spacing was too small, breaks in one fiber caused breaks in the adjacent fiber. In conclusion, using multiple fibers in a fragmentation test has many merits, such as saving time in testing, ease of comparing the effects of fiber surface treatment, and testing different fibers in the same matrix exposed to the same processing conditions.