A growing number of United Nations peacekeeping operations have become multidimensional in nature, composed of a range of components, including military, civilian police, political affairs, rule of law, human rights, humanitarian, reconstruction, public information, and gender. There are also a number of areas, such as mission support and security and safety of personnel, that remain essential to peacekeeping regardless of a particular mission’s mandate. This handbook is intended to serve as an introduction to the different components of multidimensional peacekeeping operations. It is not intended to provide strategic or policy guidance. Rather, it is intended to provide field personnel who are new to the United Nations, or who are being deployed to one of our multidimensional peacekeeping operations for the first time, with general background on the responsibilities of each component of our operations and how these fit together to form the whole. We have tried to make the handbook as brief and practical as possible while doing justice to the broad areas of work in which many operations are engaged.