A systematic approach was used to study and compare the bonding of an ethyleneoctene random copolymer and a low-density polymer, injection molded over polypropylene homopolymer. Wide ranges of overmolding and cooling interface temperatures and packing pressures were explored. Standard peeling tests were conducted at room temperature on overmolded samples, to measure the bonding strength. Large differences were found for bonding strength for both ethylene-based polymers, which are explained on a molecular basis. The analysis of the experimental results gives strong indications about the bonding mechanism and the temperatures and time scale involved in the process. Simple, reliable rules to design the overmolding process parameters for these polymers pairs are developed. (C) 2004 Society of Plastics Engineers.