Weakness in corporate governance and lack of transparency are often considered causes of, or contributors to, the Asian Financial Crisis. Publicly listed companies in Indonesia, like other Asian firms, have a concentrated ownership structure. Focusing on manufacturing firms listed on the Jakarta Stock Exchange (JSX) for the year 2003, this study adopts an agency framework to examine voluntary disclosures included in the annual reports of 149 Indonesian firms and their relationship to various attributes such as: ownership structure; whether a firm is family-owned or not; the owner's involvement in either the Board of Commissioners or Board of Directors; and whether the firm is affiliated with a business group. The results mostly support the notion that ownership structure affects the extent of disclosure in annual reports. First, the results show that, compared to firms with a nonmajority ownership structure, voluntary disclosure is lower in firms with a majority ownership structure. Second, the results indicate that family owned firms are more likely to exhibit lower voluntary disclosure than are non-family owned firms. Third, the analysis shows that, among family firms, firms with a majority (compared to those with a non-majority) ownership structure are more likely to have lower levels of voluntary disclosure. Fourth, the results indicate that, among family firms, firms affiliated with a business group are more likely to make lower voluntary disclosures than independent firms. In contrast, the empirical analysis failed to support the hypothesis that, among family firms, voluntary disclosure would be lower in firms where the owners are involved in the Board of Commissioners compared to those where there is no owner involvement in the Board of Commissioners. Similarly, the results failed to support the hypothesis that, among family firms, voluntary disclosure would be lower in firms where the owners are involved in the Board of Directors compared to those where there is no owner involvement in the Board of Directors. Robustness checks performed using alternate measures of disclosure and the degree of ownership structure did not substantially change the conclusions. This thesis contributes to our understanding of how family firms are governed and the impact of corporate governance on a firm?s level of voluntary disclosure. The results have implications for policy makers and regulators in Indonesia striving to improve corporate governance and transparency.