A Methodology for Environmental Impact Minimization (MEIM) is presented in this paper. The methodology, which embeds Life Cycle Analysis principles within a process optimization framework, involves proper definition of a consistent boundary around the process of interest, identification of the emissions inventory, quantification of environmental impact via proper metrics (for air and water pollution, solid waste, global warming and ozone depletion) and inclusion of environmental criteria within process modelling and optimization tools. A case study, the production of VCM from ethylene, is presented to illustrate the basic features of MEIM.