This paper examines firm turnover and productivity growth in the Canadian retail trade sector. Firm turnover occurs as the competitive process shifts market share from exiting firms and existing firms that contracted to entering firms and existing firms that expanded. There is considerably more firm turnover in the retail sector than in the manufacturing sector and more of it comes from entry and exit. Moreover, contrary to the manufacturing sector where only part of overall productivity growth comes from firm turnover and the re-allocation of resources from the less to the more productive, all of the aggregate productivity growth comes from this source in the retail sector. This suggests that the much-discussed Wal-Mart effect on retail sector productivity mainly comes from the Wal-Mart-created competitive pressure that shifts market share from exitors and declining incumbents to entrants and growing incumbents. Foreign-controlled firms contributed 30% of labour productivity growth and 45% of multifactor productivity growth in the retail trade sector in the period from 1984 to 1996, which are mainly due to the entry of foreign-controlled firms and expansion of more productive foreign-controlled existing firms.