Book excerpt: Worldwide, there is a vast but fragile earthen heritage that is barely surviving due to serious damage of the fabric. It is generally believed that natural agents are the overall cause for the decay of earthen heritage. However, when thoroughly evaluating, it can be observed that conservators’ interventions have a major impact, which leads to question current approaches to conservation and the reasons why intervention mistakes are repeated and why successful conservation results are still scarce. The research methodology of this investigation is based in a case study strategy analysing three World Heritage earthen sites, namely Chan Chan in Peru, Aït Ben Haddou in Morocco and Arg-e Bam in Iran. A combination of sources was also used, following a multi-method approach. This book suggests implementing standards for high quality intervention through the definition of criteria for decision-making and indicators of quality and best practice, as well as clarification concerning procedures in the methodology of intervention. It also stresses the importance of conservation theory in earthen heritage conservation, combining theory and practice. In addition, the book recommends an overall strategy in the conservation of earthen heritage, with particular emphasis on an approach that integrates education, awareness, research and preventive conservation.