Scholars generally agree that interest groups are active and at times influential during the notice and comment period of regulatory policymaking (or “rulemaking”). But current research often ignores the agenda setting that may take place during the pre-proposal stage of rulemaking. During proposal development, interest groups may lobby to: (1) influence the content of proposed regulations or (2) block items from the regulatory agenda altogether. This article focuses on ex parte lobbying—”off the public record” conversations in which lobbyists share policy and political information with regulators—during the pre-proposal stage of rulemaking. I assess the importance of ex parte influence with data from a content analysis of government documents drawn from seven federal government agencies and a telephone survey of interested parties. Overall, the findings provide the first empirical confirmation that “off the record” lobbying can, and at times, does matter to regulatory content changes during a stage of the American policymaking process that is often overlooked by scholars and the public: the pre-proposal stage of agency rulemaking.