Comparative studies were made of the residue and the fraction volatile at pyrolysis temperature, involatile at ambient temperature obtained from polystyrene and poly(p-N,N-diethylaminostyrene) degraded under identical conditions. Poly(p-N,N-diethylaminostyrene) yielded a crosslinked glassy residue after pyrolysis at temperatures greater than 250°C, and crosslinking is accompanied by N-alkyl group scission as shown by mass spectrometry. The components of the fraction volatile at pyrolysis temperature, involatile at ambient temperature were separated and identified by GPC and mass spectrometry. Mechanisms involving N-alkyl and N-aryl bond scission are proposed to account for the observed products. Quantitative studies on the effect of pyrolysis temperature and polymer molecular weight on the residue and the volatile fraction are described and discussed. No molecular weight dependence was observed for this system in the range studied.