Until recently, philosophers tended to be suspicious of the concept of need. Contributors to this volume build on recent work establishing its philosophical importance. David Wiggins, Gillian Brock and John O'Neill propose remedies for some mistakes made in ignoring or marginalising need, for example in need-free theories of rationality or justice. Christopher Rowe, Soran Reader and Sarah Miller highlight insights that emerge when the concept of need is explored through Plato, Aristotle and Kant - and others that emerge when historical work is seen through the lens of need. Jonathan Lowe and Garrett Thomson consider the role need plays in the philosophies of action and mind. Bill Wringe, David Braybrooke and Sabina Alkire debate how our obligations relating to need are best understood and articulated, and how we can best ensure they are fulfilled, exploring for example how talk of need is related to talk of rights, well-being or capability.