Actions by both private sector organizations and legislators in recent years have highlighted the importance of the audit committee of the board of directors of corporations in the financial reporting process. For example, the Sarbanes Oxley Act of 2002 has multiple sections that deal with the composition and functioning of audit committees. My dissertation examines multiple issues related to the composition of audit committees. In the first two parts of my dissertation, I examine the stock market reactions to disclosures of audit committee appointments and departures in the 8-Ks filed with the SEC during 2008 and 2009. I find that there is a positive stock market reaction to the appointment of audit committee directors who are financial experts. The second essay investigates the cumulative abnormal return to departure of audit committee directors. I find that when an accounting expert leaves the audit committee, the market reaction is significantly negative. These results are consistent with regulators’ concerns related to having directors with audit, accounting and other financial expertise on corporate audit committees. The third essay of my dissertation examines the changes in audit committee composition in the last decade. I find that while the increase in audit committee size is relatively modest, there has been a significant increase in the number of audit committee experts and the frequency of audit committee meetings over the past decade; interestingly, such increase in the number of meetings has persisted even after the media focus on the auditing profession, in the immediate aftermath of the Enron and Andersen failures, have waned. My results show that audit committee composition and its role continues to evolve with regulatory and other corporate governance related changes.