In the product life cycle assessment, evaluating the results from the inventory and impact assessment is the central issue. It is sensible to approach this problem from an interdisciplinary perspective. This book uniquely combines life cycle assessment methodology (ISO 14040 et seq.) with areas of decision theory. The application of decision-theoretical methods serves to transparently and verifiably select the most environmentally friendly product alternative while considering societal values. Based on the analysis of various stakeholder models, a proposal for the participation of societal interest groups is also developed. Both thematic focuses are summarized in a practical proposal for modified life cycle assessment and illustrated through a case study and a survey. The evaluation approach serves decision-making.