The present invention is directed to processes of polymerizing olefin monomers and copolymerizing olefin monomer(s) with functionalized alpha-olefin monomers in the presence of certain late transition metal pyrrolaldimine chelates, especially bidenate ##STR1## or in the presence of a combination of a transition metal in its zero valence and a pyrrolaldimine represented by the formula: ##STR2## wherein each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, M and L are defined in the specification herein below.