My thesis studies the changing competitive structure of the Canadian auditing industry during the period 1987 to 1992. Two mergers took place over this period amond four large Canadian accounting firms. I assess whether market power is likely to become a problem with already high, and possibly increasing levels of concentration in the audit industry. Using data from several sources, I examine those characteristics that affect the likelihood that high concentration facilitates market power. I then apply the official standards (Merger Guidelines) for Canadian merger analysis to data on audit services. Because the Merger Guidelines expressly do not permit the authorities to oppose a merger merely on structural grounds, I supplement my structural analysis with a review of studies which examine whether audit fees are influenced upward by high concentration. Overall, I found the industry more competitive in the post merger period. / xii, 149 leaves : ill. ; 28 cm.