The presence of damage in structures made out of composite and/or piezoelectric materials can cause significantdegradation in structural performance. In the present paper, damage indices based on two-dimensional gapped smoothingtechnique and model strains are developed in order to enhance the accuracy in predicting the location and extent ofdamage in composite structures. Structural analysis is performed based on a refined higher order theory, which cancapture the transverse shear effects in anisotropic laminates. An approach using the developed damage indices and thelaminate model of the higher order theory is employed to model and identify delaminations in composite laminates. It isalso used in the delamination analysis of composite laminates with piezoelectric actuators. The proposed modal strainbased damage indexes are used to perform delamination analysis. Comparison study is performed to illustrate that thereliability and robustness of the new proposed damage indices in locating delaminations in composite and smartcomposite structures. The effects on modal strain and damage indices due to the presence of surface boundedpiezoelectric actuators are also presented and discussed.