A graft copolymer with a polynorbornene backbone and deuteriopoly(ethylene oxide) grafts has been spread on aqueous subphases with dissolved hydrogenous poly(ethylene oxide) at different concentrations. The surface pressure isotherms of the spread film are very different from that obtained on water alone. A negative surface pressure is initially observed and a zero surface pressure is obtained only at a higher surface concentration of the spread graft copolymer, indicating the expulsion of dissolved poly(ethylene oxide) from the near surface. At a higher surface concentration of the graft copolymer, there is a "phase transition" in the isotherm, the surface concentration at which this is obtained depending on the concentration of poly(ethylene oxide) in the aqueous subphase. Neutron reflectometry has been applied to determine the distribution of the deuterated ethylene oxide segments as a function of the surface concentration and poly(ethylene oxide) concentration in the sub phase. The graft layer consists of a uniform composition region with a parabolic "tail". The thickness of the uniform region is smaller than that obtained in the absence of dissolved polymer and at the highest poly(ethylene oxide) concentration in the subphase the dimensions of this layer are reduced relative to those for the lower concentrations of poly(ethylene oxide). The extent of the parabolic decay region is not significantly influenced by the dissolved polymer but the maximum thickness of this region is reached at a lower surface concentration compared to that for the graft copolymer spread on water. The dissolved polymer appears not to provide screening in this parabolic region but instead is a source of additional excluded volume interactions that cause the extension of the poly(ethylene oxide) grafts.