This paper deals with modeling of an Active Limited Slip Differential (ALSD) which comprises a wet clutch actuated by an electromechanical mechatronic system consisting of a DC motor and ball-ramp mechanism. The structure of the proposed ALSD model is divided in two subsystems: (i) clutch axial force development model and (ii) clutch torque development model. The former includes DC motor dynamics; gear box kinematics and backlash; ball-ramp mechanism kinematics, friction, and compliance; fluid squeeze speed dynamics; and clutch pack axial compliance and damping. The latter includes structural compliance and inertias, as well as dynamic friction effects. Each submodel has a pure physical structure. This facilitates model parameterization through a series of relatively simple experimental procedures, which are also described in the paper. The final model has been validated under various operating conditions by using an ALSD test rig. The validation results point to a good modeling accuracy.