Social and political scientists are involved in an extensive but inconclusive debate about the role of international nongovernmental organisations (NGOs) in European migration governance. The European Union (EU) and NGOs work under the assumption that NGOs are crucial to migration governance and yet the role of NGOs is not clear. The EU has invested time and money in its attempts to involve NGOs more actively in migration governance, but it does so without much knowledge of how ngos in the past have influenced migration governance, and thus with no idea if the current investments are worthwhile. In this article, which is the introduction to the special issue on this subject, we take a closer look at the NGOs involved in West European migration in the period from the 1860s until the present day in order to understand the changing role of NGOs in migration governance in Europe. Providing moral, logistical and expert authority in a purportedly impartial way, NGOs have added a dimension to migration governance that states cannot replicate. As a result, the number of NGOs has gradually increased and at times their influence has become significant. However, in providing a chronology of the involvement of NGOs in migration governance, we show that their influence on migration governance policies and practices has not been linear. During some windows of opportunity (e.g. in the immediate years following the First and Second World Wars and the Cold War), NGOs became more prominent and effective, while at other times (e.g. the 1930s), their importance waned. The presence and capacity of NGOs to contribute to migration governance depended on whether states, and increasingly after 1945, intergovernmental organisations such as the UN, needed them to further their own interests or to fulfil a role that they could not play.