This study examines the impact of board composition on the level of voluntary disclosure in the annual reports of listed Jordanian firms. Content analysis is used to collect the required data form the 2012-annual reports of 103 firms listed on the Amman Stock Exchange. Overall, the empirical evidence provided by the study is in line with the agency theory predictions. Furthermore, they have practical implications for firms and regulators in Jordan on the importance of the board of directors and voluntary disclosure as control mechanisms for mitigating the effect of the information asymmetries and agency problems. The study shows a moderate level of voluntary disclosure in the annual reports of Jordanian firms. However, insurance firms tend to disclose more voluntary information than industrial and services firms. Also, the results suggest that Jordanian firms with a high-level of board ownership concentration tend to keep the level of voluntary disclosure low. On the other hand, the presence of foreign directors on the board seems to influence, positively, the level of voluntary disclosure in Jordanian firms. Likewise, the proportion of the old directors on the boards in Jordanian firms is very high and is significantly associated with a higher level of voluntary disclosure.