Non-governmental organisations (NGOs) are becoming more and more important in international politics. They continuously increase in size, number and influence. However, NGOs have official relations with international governmental organisations (IGOs) only. Therefore, the UN as the largest global IGO, serves as an adequate transparent point of observation to explore the realm of the 'phenomenon NGO'. As most IGOs, the UN offers the 'consultative status' to NGOs. In this work, the relationship between NGOs and IGOs will be examined in detail through the case study of NGOs and the UN body for educational, scientific and cultural questions (UNESCO), since this IGO has been widely recognised for its outstanding propositions to accredited NGOs, such as the provision of direct subventions, office accommodation and inclusion in various stages of planning and executing projects. Since UNESCO commenced a long-term reform process in 1988, the IGO itself gained in attraction to such an extent, that countries like the UK re-entered the once highly controversial organisation. The findings of this research on NGOs and UNESCO, however, reveal that UNESCO created many of its closest and most-favoured NGOs itself, and that the IGO used the 1995 re-classification of NGOs to get rid of more than one-third of all formerly accredited NGOs at UNESCO. The findings will be reflected in the light of International Relations Theory.