The effect of extent of degradation of poly(m-N,N-dimethylaminostyrene) on the quantity and molecular weight of the residue is described. Comparative studies on polystyrene and poly(m-N,N-dimethylaminostyrene) have indicated significant differences between the two polymers. Torsional braid analysis has shown the crosslinked residue from poly(m-N,N-dimethylaminostyrene), produced at temperatures greater than 150°C, to be obtained on the heating cycle rather than the cooling cycle, and mechanisms to account for this phenomenon are discussed. The physical form of the residue has been found to be molecular weight dependent, and this has been discussed in terms of the differences in “melt temperature” relative to the “onset temperature” for crosslinking. The quantity and composition of the fraction volatile at pyrolysis temperature, involatile at ambient temperature are discussed. The components of this fraction were identified by GPC and mass spectrometry and include oligomers containing the secondary amino function. Mechanisms involving N-alkyl and N-aryl scission are proposed to account for the observed products.