Previous research has reported conflicting results on whether or not foreign-owned firms diverge from indigenous firms with respect to their human resource policies and practices. Set in the dynamic, globalized economy of the Republic of Ireland, this study examines the relative use of high performance work systems (HPWS) by foreign-owned versus Irish-owned firms. We also investigate the implications of HPWS use for organizational effectiveness. Results suggest substantial differences associated with country of ownership. Relative to Irish-owned firms, foreign-owned firms report higher HPWS utilization and higher rates of workforce productivity and innovation. Results suggest that the relationship between country of ownership and organizational effectiveness is mediated by the use of HPWS.