This article looks at the role that the European Parliament, as the only democratically elected EU institution, plays in ensuring transparency in the EU’S newly concluded free trade and investment agreements (FTIAS). Using the empirically tested findings of political scientists, the article puts forward several normative claims. First, the European Parliament should ensure that the FTIAS provide high levels of participatory transparency that allows members of the ‘public’ to actively observe and take part in the international decision-making process. Second, if the participation of members of the general public is not feasible, then at least certain members of the European Parliament should be able to observe the international decision-making process and submit observations. Third, if a deliberative democratic ideal is difficult to reach, legitimacy can still be guaranteed by providing public access to the reasons for taking an international decision, after the decision has been taken. In light of these normative claims, the article discusses the transparency provisions the European Parliament should ensure are included in the parts of the FTIAS that deal with the proceedings of investment courts, the workings of treaty committees handling investment protection and the selection of the arbitrator/judge for investment courts. Proposals are also made for how the European Parliament should achieve these.