We assert that audit quality can be improved to the extent that social norms for honesty and responsibility are activated in the auditor. To test this assertion, we use an experimental audit market setting found in the literature and manipulate factors expected to activate honesty and responsibility norms in the auditor. We find that auditor misreporting is reduced when the investor is another participant in the experiment rather than computer simulated, and thus, the interests of third-party investors are salient to (...) the auditor. We also find that auditor misreporting is reduced when the auditor is required to sign-off on the audit report, but only when the investor is another participant in the experiment. Consistent with our underlying theory, we find that pre-experimental measures of sensitivity to honesty and responsibility norms help explain the effects of our manipulated variables. Finally, we find that these measures of social norm sensitivity are associated with the moral judgment that auditor misreporting is unethical. Our study helps explain previous anomalous findings in the literature and answers the call in Blay et al. for empirical researchers to use social norm theory to develop stronger tests of moral reasoning in the market for auditing services. (shrink)