This article discusses the diplomacy and foreign policy of neutral actors in international relations. It introduces popular research themes of neutrality studies and presents some of the relevant literature. Neutrality has been most profoundly developed, studied, and defined under international law. However, there are other dimensions to it like politics, ethics, norms, identity, and security under which it remains a relatively fuzzy concept. The Finnish president, Urho Kekkonen, once explained it best: “There are as many kinds of neutrality as there are neutral states.” That is because the concept has diplomatic implications that do not stem directly from a country’s abstention from conflicts, but rather from strategic or ideational factors like the normative self-conceptualizations of peoples living in neutral countries and the political choices they make. In this respect, much research on the motivations and development of individual neutralities has been conducted over the years, including case studies, comparative works, theoretical treaties, and general histories. The focus of this article lies on the development of the concept since the maritime and Great Power neutralities of the 18th century. In particular, it covers the major literature of the past one hundred years, during which neutrality in the classic sense of international law underwent several changes and new forms of the neutral idea emerged in the form of nonalignment and neutralism. Furthermore, neutrality also has a place in the history of international organizations like the United Nations or the Organization for Security and Co-operation in Europe (OSCE) and humanitarian institutions like the International Committee of the Red Cross. Therefore, this article understands “diplomacy” in a loose sense, including the foreign policies of states and the international political approaches of non-state actors alike. It defines “neutrality” as an actor’s military noninvolvement in third-party conflicts, especially in interstate wars. Hence, neutral diplomacy refers to the coordinated activities of international actors who remain—or try to remain—at a distance from third-party conflicts. The article does not cover technical understandings of neutrality that do not refer to a subject’s exclusion from conflicts but to different principles. For instance, “net-neutrality,” refers to the non-discrimination of Internet access speeds, not to the Internet’s exclusion from conflicts, and will not be covered in this analysis.