H-1 and C-13 NMR have been used for the quantitative determination of methylene-ether bridges in melamine-formaldehyde (MF) resins. The amount of methylene-ether bridges was determined by C-13 NMR from the number of monomethylolated amino groups consumed in the condensation reactions and is in agreement with that calculated from the condensation water contents. This latter method, which involves a combination of H-1 and C-13 NMR, is based on the amount of condensation water released during the formation of both methylene and methylene-ether bridges.