Failure to control for a firm’s incentives to adopt IAS when making comparisons of accounting quality between IAS and NIAS firms in the post adoption period and changes in accounting quality for IAS firms between the pre- and post adoption periods can lead us to infer that the observed differences in accounting quality are attributable to differences in the financial reporting system when the quality differences are attributable to the effects of firms’ incentives. Although we include research design features to mitigate the effects of incentives, we cannot be sure that our findings are attributable to differences in the financial reporting system rather than to differences in firms’ incentives.