This study seeks to answer the question of how to explain voluntary disclosure of companies listed on an emerging capital market. It intends to investigate the extent of voluntary disclosure especially that of Thai listed companies, and the influence of company characteristics, financial attributes, and corporate governance related factors on voluntary disclosure practices. The objectives of this research are (i) To evaluate voluntary disclosure practices of Thai listed companies over the period 1995 to 2005. (ii) To examine the contribution of company characteristics, financial attributes and corporate governance related factors in explaining variation in the extent of voluntary disclosure. (iii) To investigate perceptions of persons positioned to influence voluntary disclosure in order to obtain further insights into voluntary disclosure practices of Thai listed companies. This study applies an empirical approach to investigate voluntary disclosure practices of Thai listed companies. The quantitative and qualitative methods are employed in order to provide the best understanding of the research problems. This study intends to combine the benefit from obtaining perception towards voluntary disclosure from a semi-structured interview with a quantitative data analysis derived from a self-constructed disclosure index. Results from the qualitative analysis are used to confirm the results and enhance the interpretation of the results from the quantitative analysis. The examination of the extent of voluntary disclosure in corporate annual reports reveals that even among the most actively traded stocks on the SET, there was considerable variability in the amount of information voluntarily disclosed. By using the univariate and multivariate analyses, significant variables that explain variation in voluntary disclosures are found to be company size, type of industry, and CEO/Chairman role duality. The results also suggest that variation in voluntary disclosure could be influenced particularly from differences in time periods, especially period before and after the 1997 financial crisis. Of the three specific information categories, non-financial information is most explained, while financial information is least explained by the variables specified in the model. Results on specific information disclosure tend to support those reported at the overall level. The results also support the relative applicability of disclosure theory, especially the agency theory in explaining variation in voluntary disclosure. The interview findings suggest that voluntary disclosure behaviour is more complicated than previously assumed by the quantitative study. The opinions of preparers, users and regulators help to validate and complement the interpretation of statistical findings. The interviewees reveal some areas that could influence voluntary disclosure decisions which have not been included in the quantitative study. This study contributes to the literature by providing empirical evidence on voluntary disclosure practices of Thai listed companies, as an example of the emerging capital market in economic transition. Results from statistical analysis, together with perceptions of the influential individuals interviewed, provide a better understanding of voluntary disclosure practices. The examination of voluntary disclosures at the disaggregated level, which has not been observed thoroughly in the Thai context, contributes to in-depth understanding of disclosure behaviour and helps to validate the findings of disclosure at the aggregated level.