Grafting can be initiated by primary and/or polymer radical attack on the backbone polymer and it is well known that AIBN does not readily promote grafting, even when using polybutadiene. We have studied the grafting of several different monomers onto cis-polybutadiene using AIBN initiator and find dramatically different results among the monomers. As expected, styrene grafts at very low levels due to the inactivity of the initiator radicals and the polystyryl radicals. Methacrylate monomer grafts at a slightly higher level due to its more reactive polymer radical, while acrylate monomer readily grafts onto the polybutadiene because polyacrylate radicals are quite reactive. The use of a kinetic model allowed the evaluation of rate coefficients for graft site initiation to be in the relative order of 0.1 : 1.0 : 10.0 (L/mol/s) for styrene:methacrylate:acrylate monomers. The model also provided successful interpretations of the grafting data and its dependence upon the concentrations of monomer, initiator, and backbone polymer. Due to the relatively higher reactivity of the polyacrylate radicals, the benzene solvent acted as a chain transfer agent in this system. This affected the molecular weight of both free and grafted acrylate polymer and also surpressed the graft level. Polyacrylate radicals attack the cis-polybutadiene backbone by abstracting an allylic hydrogen and also adding across the residual double bond. The latter mechanism is responsible for the majority of the grafting; the hydrogen abstraction leads to relatively inactive radicals which cause a retardation in the overall reaction rate.