This paper investigates the coupled lateral-torsional vibration of a gear-pair system supported by a cavitated squeeze film damper (SFD). Both steady state and transient dynamic characteristics of the system are analyzed. In order to gain insight into the dynamics of the system, the free vibration frequencies and modes of the linearized system are first determined. Then, the response of the nonlinear system is examined under mass unbalance and torque excitation. The trigonometric collocation method (TCM) is employed to obtain periodic steady-state responses. Direct integration is also used in order to verify TCM and capture transient response. A comparison of the steady state responses obtained with the present model by first considering only the lateral vibration and then including torsional effects demonstrates the need to include the coupling between lateral and torsional motion. Then, the effect of parameters such as gear mesh stiffness and damping, clearance-to-diameter ratio of the SFD and gear mass unbalance on the steady state response is also presented. It is found that the mass unbalance excites not only lateral-dominated modes of the coupled system but also torsional-dominated modes. Further numerical results show that the modes of the coupled system which are dominated by lateral motion can be attenuated by using a SFD, while the modes dominated by torsional motion can be substantially suppressed by gear mesh damping. Finally, the presence of multiple solutions and complex response is predicted in some frequency ranges.