Recent work on coalition governance claims that government parties use the chairs of parliamentary committees to ‘shadow’ ministers and thus to monitor coalition partners. This argument rests on the assumption that committee chairs enjoy special powers to extract information from ministries and to affect policy-making in committee. To test this assumption, the paper develops the first comparative measure of committee chair powers in fifteen Western European democracies. The analysis shows that most committee chairs have very limited formal powers and that the share of shadowing chairs does not increase when committee chairs are more powerful. Both findings cast doubt on the interpretation of shadow chairs as a monitoring device. We sketch an alternative explanation according to which coalition parties employ the shadowing strategy in order to increase public visibility and to counteract issue ownership by the minister’s party.