A cushion for a respiratory mask assembly includes a breathing chamber forming portion and a face contacting portion formed in one piece of an elastomeric material, and a gusset portion including one or more folds. The breathing chamber forming portion includes a mask interior breathing chamber and the face contacting portion is structured to engage a patient's face. The gusset portion is structured to provide flexibility to the face contacting portion. The breathing chamber forming portion includes a front side of the mask and the face contacting portion includes a rear side of the mask. The breathing chamber forming portion, when provided to a mask frame, includes an exterior surface exposed at the front side of the mask.