AbstractWe investigate the relation between audit committee (AC) quality indices, financial reporting, internal control quality and firm value using a US dataset for the period 2002–12. The indices are developed by linking firm value with principal component analysis (PCA) factors based on a broad set of 82 AC variables, some of which influence the quality of the AC, but are not addressed in prior literature. Significant AC factors include ‘overlapping directors’, ‘busyness’ and ‘foreign director’, and we use these factors to develop ‘high’ and ‘low’ AC quality indices. We show that low AC quality firms are more likely to manage earnings, be external auditor dependent with respect to non‐audit tax services, and switch to a lower quality auditor. Low AC quality firms are also more likely to have internal control concerns disclosed by predecessor auditors, including accounting issues, financial restatements, audit opinion concerns and deficiencies that undermine internal control effectiveness. Further, they are more likely to receive an audit report containing additional explanatory notes. Conversely, high AC quality firms are significantly less likely to have these concerns. Our findings highlight the value of using AC quality indices in delivering greater oversight of the financial reporting process.