This study aims at developing a generalized elasto-plastic constitutive model for clays able to describe stress-strain response, accumulation of permanent deformations, and excess pore pressure in monotonic and cyclic loading. This constitutive model takes advantage of the nonlinear elasticity and bounding surface plasticity concepts to mimic generation of excess pore pressure and plastic deformation within the yield surface upon cycles of unloading and reloading during cyclic excitation. The generalized formulation of the model also facilitates the prediction of multi-directional cyclic response of the fine-grained material. Capabilities of the model are evaluated using the available experimental database on Boston Blue Clay (BBC). The model is successful to mimic a wide range of monotonic drained and undrained stress paths as well as the complicated cyclic response of clays. Implementation of the model in numerical packages will facilitate the simulation of different boundary value problems under various loading conditions.