The production and consumption of plastics has seen an exceptional growth over the past decades. Simultaneously, concerns around the need for sound management of plastic wastes to prevent adverse effects on environmental and human health and resource use have emerged. This thesis aims to develop a thorough understanding of the societal flows and waste management of plastics to evaluate the potential of a national waste management system to mitigate the environmental problems caused by plastic wastes, using Austria as a case study. In the first step, the general structure of the plastics economy in Austria is analysed for 2010 to identify the major processes handling plastics and to quantify the flows connecting these processes. This shows that the primary production of polymers amounted to 1100 kt/a, whereas the total plastics consumption in Austria equalled 1300 kt/a. Packaging was the most important application and was responsible for about half of the post-consumer waste generation, while the building & construction sector was responsible for by far the largest stock increase. Two thirds of plastic wastes were incinerated with energy recovery, while the remaining waste was recycled mechanically and chemically. The second step analyses the plastic flows and its composition in the Austrian waste management system for 2013 in more detail, for the sector that produces the largest amount of plastic wastes, packaging. This waste stream amounted to 300 kt/a, half of which was composed of large and small films while one third consisted of small hollow bodies, including PET bottles. The polymer composition was consequently dominated by LDPE (46 %), PET (19 %) and PP (14 %). 34% of the waste was sent to mechanical recycling, which achieved the current recycling target but leaves large improvements needed to reach the recently increased targets of 50% and 55% by 2025 and 2030, respectively. In the third step, the waste management system for plastic packaging is investigated from an environmental performance perspective by using the material flow model developed in step two as a basis for a life cycle assessment. This shows larger benefits than burdens for the overall waste management system for 15 out of the 16 investigated impact categories, with the largest contribution to the benefits for most impact categories coming from mechanical recycling. Furthermore, the effect of changes in the recycling rate on the environmental performance is explored as well using three alternative scenarios. For ten out of the 16 impact categories, the more material is mechanically recycled, the higher the overall net benefits are. However, half of the impact categories show a decreasing marginal benefit or absolute decrease in the net benefit, suggesting that depending on the impact category, the optimal recycling rate may lie below 100 %. Furthermore, the response of the different impact categories varies widely, so no one optimal recycling rate exists across all impact categories. The effects of increasing the recycling rate on the environmental performance of the waste management system should thus be investigated in detail to create a sound basis for proposing recycling targets leading to an environmentally optimal outcome.