We report the reactivities of a comprehensive range of polar vinyl comonomers and 1-olefins in the copolymerization with ethylene by [{(o-MeOC6H4)(2)PC6H4SO3}PdMe(L)] from pressure reactor studies (95 degrees C, 3-20 bar), as defined by r(E) = k(ethylene)/k(comonomer) from Markov statistics. C-13 NMR chemical shifts of the monomers' beta vinyl carbon atom and Charton and Sterimol parameters were found to be appropriate descriptors for the monomers' electronic nature and steric demand, respectively. A comprehensive picture of their impact on monomer reactivity and also regioselectivity of insertion arises. This shall also allow for predictions of the reactivity of other monomers.