Moderators are widely thought to be crucial to the facilitation of high-quality democratic debate, particularly in government-sponsored participatory exercises. There are, however, persistent fears that moderators censor rather than promote free speech, leading to a ‘shadow of control’. This article analyses the relationship between moderation and censorship on two British central government online discussion fora: Downing Street's Speaker's Corner and Policy Forum, and Citizen Space's E-Democracy Forum. Two models of moderation are developed to help structure the analysis. The main conclusions are that moderation strategies must be clearly linked to the policy goals behind the forum, and that the moderator's roles should be separated to limit the so-called ‘shadow’. The censorial role being conducted by an independent body, with facilitation activities conducted by civil servants linked to the policy being discussed.