Cross-polarization was used to probe the interphase morphology of polymeric methylenebis(phenylisocyanate), pMDI, adhesive cured with yellow-poplar (Liriodendron tulipifera) wood. A C-13 labeled and partially deuterated pMDI was synthesized in order to detect cross-polarization, CP, from wood protons to cured resin. Under particular conditions, pMDI samples cured with wood exhibited enhanced CP, as compared to neat cured resin. The occurrence of enhanced CP was a function of the cure temperature and also a time delay between resin application and cure. The enhanced CP may be due to interpolymer transfer of magnetization. This could suggest that some degree of molecular interpenetration may exist in the interphase region. However, confounding effects related to the cross-polarization experiment require additional work to verify this possibility.