This chapter sets out the structure and practice for assessing merger review under the Canadian Competition Act. Similar to other competition regimes, the fundamental framework of analysis centres on whether a merger will, or is likely to, result in a substantial prevention or lessening of competition. We also discuss the enforcement approach taken to merger review by the Competition Bureau. Lastly, the chapter examines issues related to challenges by the commissioner of competition (commissioner) and potential remedies when issues arise. An extract from the 2011 Antitrust Review of the Americas - a www.GlobalCompetitionReview.com special report.