In this study, an analytical solution is presented to calculate interlaminar stresses in long symmetric cross-ply composite laminates subjected to uniform axial strain and thermal loading. At first, the most general form of layerwise-based displacement field is extracted by a successive integration of elastic strain–displacement relations and imposing the physical restrictions based on deformation patterns of these laminates. The equilibrium equations are then derived by using the principle of minimum total potential energy and solved analytically in order to obtain three-dimensional stress field in the laminated plate. Finally, various numerical examples are investigated in order to validate the efficiency and accuracy of the layerwise theory in predicting the interlaminar stresses. For the assessment of the accuracy of the proposed method, the interlaminar stresses are also calculated within the framework of a 3D finite element analysis using the Abaqus software. The corresponding numerical results are in good agreement with those obtained through the layerwise theory. All results indicate that the presented approaches have a good prediction capability of interlaminar stresses in interior regions of the laminate and theirs high stress concentration near its free edges that can cause delamination failure.