The dynamic response of a two degree-of-freedom system with autoparametric coupling to a wide band random excitation is investigated. The analytical modeling includes quadratic nonlinearity, and a general first-order differential equation of the moments of any order is derived. It is found that the moment equations form an infinite hierarchy set which is closed via two different closure methods. These are the Gaussian closure and the non-Gaussian closure schemes. The Gaussian closure solution shows that the system does not reach a stationary response while the non-Gaussian closure solution gives a complete stationary steady-state response. In both cases, the response is obtained in the neighborhood of the autoparametric internal resonance condition for various system parameters.