The invention encompasses a mixed transition metal olefin polymerization catalyst system suitable for the polymerization of olefin monomers comprising one late transition metal catalyst system and at least one different catalyst system selected from the group consisting of late transition metal catalyst systems, transition metal metallocene catalyst systems or Ziegler-Natta catalyst systems. Preferred embodiments include at least one late transition metal catalyst system comprising a Group 9, 10, or 11 metal complex stabilized by a bidentate ligand structure and at least one transition metal metallocene catalyst system comprising a Group 4 metal complex stabilized by at least one ancillary cyclopentadienyl ligand. The polymerization process for olefin monomers comprises contacting one or more olefins with these catalyst systems under polymerization conditions.