The European ALARA Network regularly organises workshops on topical issues in radiation protection. The topic of the 18th workshop was ‘ALARA for Decommissioning and Site Remediation’. The workshop was jointly organised with the ISOE Working Group on Decommissioning (ISOE WG-DECOM) and the French Atomic Alternatives Energy and Atomic Energy Commission (CEA). The main objective was to examine the conceptual and practical aspects of the implementation of the optimisation principle (or ALARA principle) in the ‘nuclear’ and ‘non-nuclear’ sectors and also for legacy sites. This memorandum presents a synthesis of the presentations and working groups discussion that took place. It also summaries the conclusions from former EAN workshops on the same topic (1997, 2006) to highlight the commonalities and the new topics. The theoretical scheme for applying the ALARA principle is illustrated by the various presentations of decommissioning and remediation (D&R) projects given at the workshop. The theoretical scheme includes, a starting point, the planning and implementation of the D&R strategy (including ALARA analysis) and the definition of an end-state. To lay down the foundations of ALARA, the initial characterisation should be comprehensive; considering not only radiation protection but other risks and circumstances both on site and off site. Decisionmaking is not trivial because many factors influence the D&R strategy and they can be addressed together using an holistic approach. A general methodology for such an approach in D&R was drafted by the participants. Techniques are apparently industrially mature and dosimetric data suggest that good control has been achieved, however experience shows that the D&R strategy will go through multiple adaptations along the way. The management of wastes remains a challenge in many cases as well as the decision on the end-state leading to question of what is a ‘sustainable ALARA end-state’.