In a knowledge management project, the key issue is to help the stakeholders to choose which parts of their knowledge will need to be specifically capitalized. This means finding a decision support approach enabling them to identify and locate potential crucial knowledge. To deal with this type of issue, a specific approach named GAMETH has been developed. In this article, we describe the GAMETH approach from the decision support viewpoint, showing the link with the decision process. Finally, we present GAMETH applications in two different contexts.