The demand for information and transparency from listed corporations has recently increased. In spite of an increased demand for mandatory disclosures from regulators, corporations choose to voluntarily disclose additional information in order to satisfy demands from the capital market. However, the extent and content of information in those voluntary disclosures vary across corporations. The aim of this study is to explain the variation in the content of information in voluntary disclosures by listed corporations. The analyses are based on data collected from 431 annual reports from corporations listed on the Stockholm Stock Exchange during the years 2002 and 2005. The findings support explanations from agency theory and positive accounting theory that size and the debt ratio are positively correlated with the content of information in voluntary disclosures. Corporations with a high share of management ownership disclosed less information than corporations with a low share of management ownership. The study also shows that variations in voluntary disclosures can be explained by factors derived from institutional theory and ’international capital market pressures’. The results indicate that foreign ownership and international listing to some extent have a positive effect on the content of information in voluntary disclosures. Industry was another factor that had a significant influence on voluntary disclosures. One important finding is that regulation to some extent can stimulate voluntary disclosures; our results did not indicate an ’unintended chilling effect’ due to too much regulation. In general, the corporations disclosed more voluntary information after the introduction of IFRS. © 2009 Springer Science+Business Media, LLC.