This collection on transitional justice sits as part of a library of essays on different concepts of 'justice'. Yet transitional justice appears quite different from other types of justice and fundamental ambiguities characterise the term that raise questions as to how it should sit alongside other concepts of justice. This collection attempts to capture and portray three different dimensions of the transitional justice field. Part I addresses the origins of the field which continue to bedevil it. Indeed the origins themselves are increasingly debated in what is an emergent contested historiography of the field that assists in understanding its contemporary quirks and concerns. Part II addresses and sets out parts of the 'tool-kit' of transitional justice, which could be understood as the canonical research agenda of the field. Part III tries to convey a sense of the way in which the field is un-folding and extending to new transitions, tools, theories of justice, and self-critique.