Abstract: The toughening due to energy-dissipating crack wake and bridging during crack growth is analyzed in the present paper. According to their contributions to the energy integraJ applicable to a growing crack, the toughening mechanisms for toughened structural materials can be decomposed into: dilitational plasticity and induced shear yielding along the crack wake; bridging due to second inclusion phases; and matrix bridging of a wavy crack front. Detailed toughening analysis is carried out for structural polym...