The study reported herein examines the impact of two central corporate governance mechanisms (internal audit function quality and board of directors’ quality) on the incidence of earnings management. Unlike most prior studies in the area, focused mainly on US firms, this study looks at European firms that are cross‐listed in the US and covers a long time span – before and after major changes were implemented in corporate governance policies (Sarbanes‐Oxley Act in the US and the 8th Company Law Directive in the European Union). Using novel and comprehensive measurement approaches for internal audit function quality and board of directors’ quality, we find that both mechanisms have a negative direct effect on the incidence of earnings management, while their interactive effect is positive. A longitudinal analysis of both mechanisms also reveals that internal audit function quality and the quality of boards of directors have increased significantly since the policy changes.