Today, humanitarian non-governmental organisations (NGOs) have to work in an increasingly complex and (politically) changing environment. Complex emergencies, NGO perception by local populations, security and legal constraints, humanitarian reforms, relations with the military, instrumentalisation of aid, to mention but a few, are all aspects that constitute continuous challenges to humanitarian NGOs. In such conditions, European humanitarian NGOs need to be flexible, whilst simultaneously respecting the humanitarian principles and implementing life-saving missions. This edition of VOICE OUT LOUD focuses on the various dilemmas stemming from this context. It introduces the issue of how professional NGOs address the complex environment they work in today and which constantly challenges their mandate.