the photon emission (phe) and acoustic emission (ae) accompanying the deformation and failure of model composites were investigated, and related to various failure events. unidirectional composites containing from 1 to 300 fibers were strained in tension, and photon and acoustic emission (in some cases, electron emission) monitored before, during, and after fracture. fibermatrix bond strength was varied with different surface treatments, thereby altering the mode and locus of fracture, and the resulting failure events were correlated with the emission signals. ae identified cohesive failure of fibers and matrix and provided a reference for the phe bursts. the photon signals were observed to be significantly more intense in poorly bonded specimens, and were shown to arise from adhesive failure between fibers and matrix. well bonded specimens displayed predominantly cohesive failure, with correspondingly less intense photon emission. in the cases where electron emission was recorded, signals were seen only during and following ultimate failure as opposed to phe seen prior to failure. (author abstract) 24 refs