Neutral Ni(H) salicylaldimine catalysts (pendant ligand = NCMe or PPh3) were used to copolymerize ethylene with monomers containing esters, alcohols, anhydrides, and amides and yielded linear functionalized polyethylene in a single step. alpha-Olefins and polycyclic olefin comonomers carrying functionality were directly incorporated into the polyethylene backbone by the catalysts without any cocatalyst, catalyst initiator, or other disturber compounds. The degree of comonomer incorporation was related to the monomer structure: tricyclononenes > norbornenes > alpha-olefins. A wide range of comonomer incorporation, up to 30 mol %, was achieved while a linear polyethylene structure was maintained under mild conditions (40degreesC, 100 psi ethylene). Results from the characterization of the copolymers by solution and solid-state NMR techniques, thermal analysis, and molecular weight demonstrated that the materials contained a relatively pure microstructure for a functionalized polyethylene that was prepared in one step with no catalyst additive.