Daniela Irrera explores the relationship between non-governmental organisations (NGOs) and intergovernmental organisations (IGOs). The author reviews the issue of NGOs' participation in the decision-making processes of intergovernmental IGOs and investigates new activities undertaken by NGOs, including their participation in multilateral humanitarian intervention operations, crisis management and conflict resolution. Theoretical discourse is underpinned by empirical data from a survey of representatives from 28 humanitarian NGOs and networks of NGOs that are active in the fields of humanitarian assistance and peace building, as well as conflict transformation and mediation. It demonstrates that the role of non-state actors in the deployment of humanitarian interventions is destined to grow in the near future and promotes our understanding of such a development. Academics in a wide range of fields including development, international studies and public policy will find this book to be an enlightening read. It will also prove to be of great relevance to practitioners and policymakers in NGOs, IGOs, research centres and regional agencies.