A constitutive model based on a combination of a fracture-mechanics based model and micromechanical formulations is developed to predict the crack evolution and effective mechanical behavior of damage-tolerant brittle composites. The constitutive model is cast in a rate form and considers microcrack nucleation rate and microcrack growth rate. The effective moduli of the composites containing different crack distributions are formulated using the self-consistent method and differential scheme. The constitutive model is then implemented into finite element codes to solve boundary value problems of the composites. Numerical simulations on a benchmark problem are carried out to illustrate the model features. Finally, to further assess the validity of the present framework, the present predictions are compared with experimental data on brittle composites. Published by Elsevier BN.