This book is an introduction to the wide-ranging topic of non-governmental organizations (NGOs) and development, combining a critical overview of the main research literature with a set of up-to-date theoretical and practical insights drawn from experience in Asia, Europe, Africa and elsewhere. The revised second edition highlights the continuing importance of NGOs in development, while fully engaging with the criticisms that their increased profile now attracts. It considers issues such as securitization, changing technologies, and recent concerns about safeguarding as well as going into more detail around topics such as market-based development and social enterprise. The diversity of NGOs and their roles is discussed against the broader historical background of struggles for social justice in different societies, as well as within the shifting ideological contexts of neoliberalism and populism. Using a broad range of short case studies of both successful and unsuccessful interventions, the authors analyze how interest in NGOs has both reflected and informed wider theoretical trends and debates within development studies. The book argues that NGOs are central to both development theory and practice and are likely to remain important actors for many years to come. This critical overview will be useful to students of development studies at undergraduate and master's levels in fields and disciplines as diverse as International Development Studies, International Relations, Geography, Anthropology, Global Studies, Politics and International Studies, as well as general readers and practitioners.