In this paper, the equations of motion for a twodimensional (2-D) wing encountering a gust are presented. The wing has two degrees of freedom, i.e. pitch and plunge, and its motion is restrained by nonlinear translational and rotational springs. Two different stiffness nonlinearities are examined: (i) cubic and (ii) free play. For given system parameters, the responses of the nonlinear system to the sharp-edged and 1- cosine gust profiles are obtained at different flow velocities and compared to the time response of the system with no gust input.