This publication provides guidance for application to decommissioning projects. It is structured in order to take the reader progressively through all aspects of designing, selecting and using performance indicators. A process for setting up a performance indicator system against basic principles is presented, including a discussion of each step in the process. Finally, practical guidance on the use of performance indicators in specific Member States is provided alongside field experience. While the advice is primarily for use by decommissioning project managers, its value will also be in improving the project information provided to stakeholders such as regulators and other interested groups.