Recent developments in investment arbitration and international investment law, in general, are prompting the review of the role of amici curiae in investment arbitration proceedings. The latest initiatives addressing the challenges to the investor-State dispute settlement (‘ISDS’) system, including under the auspices of the UNCITRAL Working Group III, alluded to the participation of the amici in ISDS proceedings. The new generation of international investment agreements (‘IIAs’) is also tackling an enhanced role of amicus curiae, whereas the proposal for the amendment of the ICSID Arbitration Rules includes sizeable amendments to Rule 37(2), to reflect these developments and other concerns raised so far in the practice. This paper addresses the role of amici curiae in these turbulent times for ISDS, emphasizing that, before anything, the role of these non-disputing parties is to assist arbitral tribunals.