Anion exchange resins and the corresponding precursor resins have been investigated by C-13 solid state nuclear magnetic resonance spectroscopy. Cross-polarization, single pulse excitation (SPE), and nuclear Overhauser enhancement pulse sequences in combination with magic angle spinning (MAS) techniques have been exploited. Variable temperature MAS has also been carried out in order to probe the reaction between unreacted double bonds and chloromethyl methyl ether in the presence of a Lewis acid. New resonances detected by this method have been rationalised in structural terms. The level of secondary cross-linking (methylene bridging) during chloromethylation has also been determined by the use of the inherently quantitative SPE technique at low field.