The first tools to assess agri-chains focused on their economic aspects. Following requests from professionals from different agri-chains, CIRAD undertakes original research to develop methods for the environmental and social assessment of agri-chains. Indeed, although the production of food consumes resources and causes pollution, thus leading to various types of externalities, it remains an essential activity. It also generates positive or adverse social effects. Even though some large multinational companies wish to reduce their environmental impacts or improve their social impact, their desire or willingness is not sufficient. It is necessary to evaluate the environmental and social consequences of their actions in the most relevant manner possible. This chapter focuses on life cycle assessment methods because they are suitable for a chain-based reasoning and, due to their design, are the only methods that take the transfer of impacts into account. Since the pollution emitted by an agri-chain (or areas of consumption of non-renewable resources) can be spread out over several sites, the life cycle assessment method replaces the direct measurement of emissions. These are indirect assessment methods based on benchmarks stored in databases. Several configurations are possible in order to define boundaries (at least the spatial and temporal boundaries, but also that of affected actors in the case of a social life cycle assessment) of the system that will be studied by this type of analysis. The extent of change (marginal or extensive which modifies the system’s structure itself) also influences the determination of the system’s boundaries. The variety and sophistication of tools available for this type of assessment reflects the strong and ever increasing societal demand. The assessment addresses four key requirements: strengthening one’s market power, adjusting one’s action plan, acquiring knowledge in order to decide, and the need for self-assurance.