The criticisms that have been voiced against investment arbitration have led to a growing interest in alternative means of dispute settlement, especially mediation. In 2022, as part of an overhaul of its Rules and Regulations, the International Centre for Settlement of Investment Disputes (ICSID) adopted a set of mediation rules, which are the first institutional mediation rules developed specifically for investment disputes. These rules are the focus of this chapter. The chapter reviews the context of the adoption of the ICSID Mediation Rules, before considering the reasons that may have encouraged ICSID to establish them, given that, even before 2022, the Centre provided a framework for the conciliation of investment disputes. The chapter further examines the mediation procedure under the ICSID Mediation Rules, from the initiation of proceedings to their conduct and termination, and considers remaining challenges, which it argues will need to be addressed, if mediation is to become a more mainstream means of settling investment disputes.