This publication presents information on experience and lessons learned from implementation of decommissioning projects for particle accelerators. Based on this information, and highlighting typical issues and concerns, the publication provides practical guidance for all those having a role in this process. The publication is written for operators of accelerator facilities, particularly those facilities approaching the decommissioning stage, or operators maintaining a facility in a deferred dismantling state, as well as for regulators, waste managers, decision makers at government level, local authorities, decommissioning contractors and designers of accelerators. It is anticipated that lessons learned and described in this publication will contribute to decommissioning planning during the design stage of new facilities, hence minimizing the generation of radioactive waste without compromising structural characteristics and the effectiveness of the construction.