An effective-medium theory is presented for the substitutionally disordered transverse Ising model above its transition. The equations of motion for the relevant Green functions are decoupled in RPA. The disorder then occurs through a local parameter and can be treated in the spirit of the single-site coherent potential approximation. Fully self-consistent results are computed at the transition for the transition temperature, densities of states and spectral function. Simple features of the results can be understood using a generalized virtual-crystal approximation which accounts for damping due to disorder. Extensions of the theory to include intrinsic damping, more than one spin per unit cell and coupling to phonons are discussed.