Application of Linear Programming (LP) Modelling to Life Cycle Assessment (LCA) is a novel approach to analysing and managing the environmental performance of a complete product system. Not only can it solve the problem of allocation of environmental burdens in the Inventory stage of the LCA, but it also enables the environmental optimum of the system to be investigated. Once the environmental burdens have been allocated amongst different products on the basis of marginal changes in activities, they are aggregated to quantify environmental impacts and then reduced to a single environmental impact function which is treated as a new objective function of the LP model. The LP solution then gives the environmental optimum of the system and identifies places where improvements can be made. If multiobjective LP is applied, then the environmental performance of the system can be combined with other requirements, such as societal preferences or economics, thus giving the best compromise for the system performance. The idea behind this approach is illustrated by a simplified analysis of a system to produce thermoplastics.