In its White Paper on European governance reform, the Commission made interest group participation in policy deliberation a central objective under its aim for ''Better involvement, more openness" (Commission 2001 p. 5). Increasing distrust towards politics in Brussels led the EU to adopt a series of measures to boost its democratic credentials and improve its decision making procedures. Over the past 10 years the EU expanded its use of policy deliberation mechanisms as a standard practice, and provided financial support for civil society mobilization. Beyond its inputs and outputs these actions are targeted at increasing its throughput legitimacy, the quality of governance processes; addressing concerns over issues such as biased interest group access, institutional capture by insiders, and lack of transparency (Schmidt 2013). Despite its popularity within institutional circles the remedy has been contested. Conceptually, scholars question whether such procedures can expand participation beyond established insiders (Broscheid and Coen 2003). Significantly, notwithstanding work on the Commission (Pollack 2003; Joerges & Neyer 1997; Bunea 2017) the literature misses systematic analyses normatively testing such mechanisms in other EU institutions (however, see Fasone & Lupo 2015). In particular, the European Parliament (EP) faces growing alarms over business access to such procedures, giving it an upper hand to impact legislative proposals in areas of public interest (Euractiv 2017). By concentrating discussions on Brussels' procedural (il-) legitimacy to the usual suspect in Berlaymont we treat such mechanisms in other institutions as a black box and limit the scope of the debate. In this paper, we aim to assess which interest groups access the EP's deliberative processes focusing on its hearings as an understudied area of European governance. Committee hearings are one of the few forums where the parliament invites organizations to provide information and deliberate on policy issues. Two connected questions come up: How open are hearings to interest groups? Do they include some interest groups more than others? We answer these questions by arguing that hearings can serve three ideal-type purposes which in turn impact the interest group participants. First, hearings can be used as a coordinative procedure that allows policy stakeholders and policy-makers to frame the broader discussion over an issue, in line with information-exchange models and pluralist approaches to EU lobbying (Farrel & Rabin