The present document surveys the issues related to transparency and third party participation in investor-state dispute settlement procedures. Section I examines the way in which the current rules apply to these issues. Section II describes the steps taken to improve the transparency of the system at the governmental level, by the arbitral Tribunals and the International Centre for the Settlement of Investment Disputes (ICSID). Section III examines the perceived advantages as well as the challenges of additional transparency. The last section sums up.