What are CSOs and what makes them different? This book defines CSOs as nonmarket and non-state organisations outside of the family in which people organise themselves to pursue shared interests in the public domain. The emphasis in this book is on CSOs characterised by relationships of social solidarity with marginalised populations and concern for social justice. CSOs fill a number of significant roles as development actors and as aid donors, channels and recipients. The Advisory Group on Civil Society and Aid Effectiveness recommends formal recognition of the importance and diversity of CSOs and proposes that CSOs be brought systematically into the development and aid policy dialogue.