Publisher Summary This chapter discusses how to set up the necessary documentation, especially safety documentation, required to carry out a decommissioning project. A typical set of documentation is required for a decommissioning project including a Decommissioning Plan and Program, a Decommissioning Safety Case (DSC), and a Post-decommissioning Report. The Decommissioning Plan provides a strategic overview of the decommissioning project through to its final endpoint. The end-point may be unrestricted use of the site or some other agreed condition, if complete clearance for unrestricted use is not appropriate. The Program should provide a statement of the decommissioning tasks to be carried out, together with timescales. The DSC is used to justify the safety of the proposed methods for decommissioning. The safety case should demonstrate a logical connection among the plant condition at shut-down (identifying the hazards), the proposed decommissioning tasks, the associated risks in performing these tasks, and the safety management arrangements that will minimize the risks. The modern approach to presenting safety cases requires the preparation of a Safety Report supported by a Safety Report Support File, the intention being that the safety arguments for decommissioning are presented in a succinct and clear manner.