The task environment of NGOs is changing rapidly and significantly, making new demands on their management and leadership. This Companion discusses the complexities involved. It illustrates how NGOs can maintain performance and remain agile amidst increasing uncertainties. These factors include the position of NGOs in civil society, their involvement in governance and coping with the effects of the securitisation of international aid. Complementing The Earthscan Reader in NGO Management, selected contributions and specially commissioned pieces from NGO thought-leaders and practitioners, provide the reader with insights on the emerging thinking, competences and practices needed for success in managing and leading tomorrow's NGOs.