"Ambiguities in Decision-oriented Life Cycle Inventories" is a specialized book that addresses the challenges and complexities of life cycle assessment (LCA) of products. It demonstrates that the assignment of material and energy flows to a product is not only a scientifically grounded, objective task but is also heavily influenced by mental models and values. This insight is crucial as it emphasizes the need to consider various management rules for sustainable material use. Otherwise, the improvement suggestions derived from an LCA could have negative environmental impacts when viewed in a broader context. The book develops a group modeling process that allows for capturing the mental models and values of decision-makers in the inventory analysis, thereby increasing the relevance of LCA results in the decision-making process. Two case studies on recycling models and other end-of-life options complement the methodological approaches and provide practical insights into the application of the concepts.