Electron paramagnetic resonance (EPR) examinations of the stable free radicals from the polymerizations of a series of monofunctional, difunctional, and trifunctional acrylates and methacrylates have been made. The continuous-wave (CW) EPR of polymers from selectively deuterated monofunctional monomers and the pulsed EPR of the nondeuterated polymers were also examined. The aim of the experiments was to attempt to clarify several points of disagreement concerning the identity and assignment of polymer free radicals. The EPR results on the polymethacrylates are in general agreement with past results and interpretations, in which isotropic hyperfine interactions are assigned to the methyl and methylene protons beta to the central carbon of the propagating polymer radical. The rate of propagation of the observed radicals has been arrested by the high viscosity achieved in the polymer. The CW EPR spectra of the polyacrylates are well-simulated with two different models. In one model, the spectra are assigned to the propagating free radical with isotropic beta-methylene proton interactions and an anisotropic alpha-proton coupling. In the other model, it is assumed that the secondary propagating radical abstracts a hydrogen from the polymer chain to form a tertiary radical flanked by two isotropically coupled methylene groups. The latter model gives a slightly better fit to the data. One of the unresolved problems with the EPR spectra of acrylate and methacrylate polymers has been the absence or selective broadening of certain expected hyperfine lines. One hypothesis is a dynamic polymer motion that exchanges methylene proton positions, resulting in an alternating homogeneous line width [Sakai, Y.; Iwasaki, M. J. Polym. Sci. A-1 1969, 7, 1719]. The spin-spin relaxation times, T-2, measured with pulsed EPR fail to support this hypothesis. We show that a static orientation distribution of the methylene protons with respect to the axis of the orbital of the odd electron [Best, M. E.; Kasai, P. H. Macromolecules 1989, 22, 2622] successfully leads to an alternating heterogeneous line width.