The strain-raie-dependent failure of a fiber-reinforced toughened-matrix composite (IM7/8552) was experimentally characterized over the range of quasi-static (10-4) to dynamic (103 s-1) strain rates using off-axis lamina and angle-ply laminate specimens. A progressive failure paradigm was proposed to describe the matrix-dominated transition from linear elastic to non-linear material behavior, and the Northwestern Failure Theory was adapted to develop a set of yield criteria for predicting the matrix-dominated yielding of composites using the lamina-based transverse tension (F2ty), transverse compression (F2Cy)> and shear (F6y) yield strengths. A verification and validation protocol was employed to evaluate the applicability of the new failure-mode-based yield criteria. Starting with the lamina, the proposed criteria were validated to accurately predict matrix-dominated yielding. Angle-ply laminates were investigated to isolate the matrix-dominated laminate behavior, and the predictions were found to be in superior agreement with the experimental results compared to the classical failure theories in all cases using simply determined average lamina yield properties.