This paper adopts a systems firm-centered perspective on the environmental assessment of recyclable glass and PET soft drink containers. We employ LCA and discrete-event simulation modelling for the environmental assessment of the two soft drinks packaging alternatives in operational terms, over the entire supply chain, over a period of three years. The assessment is based on real data collected from a large soft-drinks producer and its suppliers. The research and practice contribution of the paper is twofold: first, it introduces a methodological framework for environmental assessment of companies’ packaging environmental impact under different product and operations strategies, and secondly, it provides a holistic environmental assessment of the two packaging materials (PET and glass) taking into account specific operational issues, such as product mix and recycling and reuse options, and activity interdependences and stochasticity. The results of the simulation experiments confirm at system level, for glass, the importance for sustainability, to increase the number of reuse cycles and the percentage of used bottles collected for refilling, whereas for PET, to increase the percentage of recycled PET in new bottles.