Corporate managers often pursue voluntary non-GAAP reporting when mandatory reporting is limited, although regulators are concerned with how this reporting is utilized. While the level of flexibility external auditors exhibit during discussions over subjective GAAP reporting choices can influence management's GAAP reporting decisions, it is important to determine if this behavior affects subsequent non-GAAP reporting decisions. Additionally, recent calls for increased audit committee questioning of non-GAAP disclosures may also cause audit committees to influence non-GAAP reporting. In this dissertation, I conduct an experiment to examine how auditor flexibility and audit committee questioning influence non-GAAP preparation and earnings release disclosure choices of senior executives. I predict less flexible auditor behavior will enhance managers' psychological feeling of constraint, while audit committee questioning focused on non-GAAP measures can increase managers' self-assessment of reporting decisions, both of which will translate into more conservative non-GAAP reporting. However, given prior research indicating that corporate governance mechanisms can combine in complex ways, I predict a greater impact of audit committee questioning absent auditor constraint. Results indicate managers make less conservative non-GAAP preparation decisions and disclose more non-GAAP measures in the absence of constraint from inflexible auditors. However, absent this constraint, managers make more conservative non-GAAP preparation choices and present non-GAAP measures less prominently in earnings press releases when the audit committee questions non-GAAP disclosures. These results are driven by a thorough self-assessment of reporting decisions by managers expecting audit committee questioning. This study provides evidence on how external auditors and audit committees influence various voluntary reporting decisions. / Doctor of Philosophy / Corporate managers can report their company's financial information to investors and other stakeholders in various ways. Some financial information is required to be reported in accordance with a set of formal accounting standards called United States Generally Accepted Accounting Principles (GAAP). Beyond this mandatory reporting, other financial information is disclosed voluntarily when company management believes this extra information is beneficial to investors. These voluntary disclosures— called non-GAAP measures— do not follow a set of accounting standards and can be disclosed with more discretion by company management than GAAP measures. The variation in how non-GAAP measures are prepared and disclosed concerns regulators, such as the Securities and Exchange Commission (SEC). Mandatory GAAP financial reporting is overseen by external auditors from public accounting firms, but auditors typically have very little formal oversight over non-GAAP reporting. Although company management ultimately decides how to disclose GAAP information, external auditors influence these reporting decisions by recommending choices during discussions over subjective GAAP issues. Sometimes auditors exhibit inflexible behavior during these discussions by being unwilling to consider management's reporting choices. This inflexibility limits or constrains the GAAP reporting choices of managers. However, prior research has not studied how this constraint impacts how managers make non-GAAP reporting choices. Further, GAAP reporting choices can also be influenced by the audit committee, which is a subgroup of members of the board of directors that is in charge of overseeing financial reporting and disclosure. Recent calls from regulators have asked for increased audit committee questioning of non-GAAP disclosures, which may also cause audit committees to influence non-GAAP reporting. Non-GAAP measures are often presented in earnings press releases, which are public announcements by a company that disclose information regarding results of operations or financial condition for a given period. Managers can make strategic decisions regarding the preparation of non-GAAP measures and the presentation of this information in earnings releases, both of which can influence investors' decision-making. In this dissertation, I conduct an experiment utilizing senior executives to examine how auditor flexibility and audit committee questioning influence these two types of non-GAAP reporting decisions: how to prepare non-GAAP measures and how to disclose them in earnings press releases. I predict less flexible auditor behavior will enhance managers' psychological feeling of constraint, while audit committee questioning focused on non-GAAP measures will increase managers' self-assessment of reporting decisions, both of which will translate into more conservative non-GAAP reporting. However, prior research indicates that corporate governance mechanisms, which are factors intended to help direct and monitor company management (such as auditors and audit committees), can combine in complex ways. Therefore, I predict a greater impact of audit committee questioning absent auditor constraint. The results indicate managers make less conservative non-GAAP preparation decisions (i.e. are more likely to calculate non-GAAP earnings figures that deviate from their GAAP counterparts) and disclose more non-GAAP measures in the absence of constraint from inflexible auditors. However, absent this constraint, managers make more conservative non-GAAP preparation choices and present non-GAAP measures less prominently in earnings press releases when the audit committee questions non-GAAP disclosures. These results are driven by a thorough self-assessment of reporting decisions by managers expecting audit committee questioning. This study provides evidence on how external auditors and audit committees influence various voluntary reporting decisions. Given the ubiquity of non-GAAP reporting in recent years, this dissertation can provide valuable insights to regulators, investors, and other stakeholders on factors that influence managerial decision-making related to non-GAAP disclosures.