A simple micromechanics-based material model for nonlinear analysis of thick-section laminated composites is presented. The model, which has been incorporated in a finite element package, provides constitutive information for the laminate at a material point (Gaussian integration point) in a standard displacement-based isoparametric 3-D or thick-shell finite element. This integrated approach allows the use of micromechanics-based criteria for detection of failure, including compression kink banding, in the analysis of a composite structure or structural component. A nonlinear elastic power-law model is used to reflect matrix shear softening; simple maximum stress criteria are used for detection of failure in constituent phases; and the tangent shear modulus of the matrix phase (determined as a function of load level during the nonlinear stress analysis of the composite) is used in the Hahn-Williams criterion to detect compression kink banding. Numerical procedures are used to redistribute the load in damaged regions. Detailed comparisons with published numerical and experimental results are presented, including: elastic modulus predictions for a graphite/epoxy lamina; nonlinear response of unidirectional boron/epoxy laminae and laminates with various stacking sequences; and nonlinear response of a notched graphite/epoxy laminate in compression.