The continuing changing nature of conflict and violence in the past two decades, coupled with a decrease in financial resources, catapulted preventive diplomacy to the international community’s security agenda. If originally the preventive diplomacy doctrine aimed at the short-term goal of preventing violence or conflict escalation, today it has come to encompass tasks aimed at resolving the underlying issues that cause and fuel conflict. In parallel – promptly deployable and cost-effective – mediation has become a more and more sophisticated and increasingly deployed instrument of preventive diplomacy. However, there is no consensus in the literature on how high-level mediation serves preventive diplomacy goals. The question of whether preventing conflict means to prevent the onset of (armed) violence in conflict, or whether it makes sense to talk about violence prevention at later stages of the conflict’s cycle, permeates the evolution of the preventive diplomacy doctrine and literature and divides opinion in mediation literature. The following literature review aims to offer an understanding on how mediation works as a preventive diplomacy instrument by synthesizing the literature and bridging it with a contemporary understanding of the concept. It does so through a parallel review of the evolution of the concept of preventive diplomacy and its agenda and conflict mediation literary debates on mediation timing, strategy and outcomes in conflict prevention. It concludes, first, that high-level mediation is better equipped and understood as an instrument of preventive, rather than pre-emptive mediation, and denotes that while the preventive diplomacy agenda has expanded, mediation literature has tended to have a narrow view of the extent to which mediation can contribute to preventive diplomacy goals.