A recently developed force field has been employed to interpret the vibrational spectra of methylolmelamines and their bridged oligomers in melamine-formaldehyde adducts and resins. The results show that some surprising experimentally observed features, such as the apparent insensitivity of one of the ring breathing modes and the very strong sensitivity of the other ring breathing mode upon methylolation, can be fully recovered from the calculations. Most, although net all, assignments based on the present calculations are in agreement with previous assignments based on purely experimental data. It is thus shown that vibrational analysis with a good quality force field can significantly contribute to a further understanding of the spectra of complex systems such as melamine-formaldehyde resins.