This article provides an empirical test of an informational model of lobbying. The model predicts when lobbyists provide useful information to policy makers and when policy makers follow lobbyists' advice. The predictions are assessed against data on the policy positions and lobbying activities of firms and other organised groups in the context of 28 policy proposals advanced by United Kingdom governments between 2001 and 2007. The results suggest that the interactions between policy makers and lobbyists are driven mainly by the expected policy costs for policy makers, providing lobbyists with strong incentives to provide correct advice to policy makers. There is little support for the expectation that lobbyists can successfully persuade policy makers to take a course of action that is beneficial to the lobbyist at the expense of wider constituencies.