Submitted to Management Science manuscript Efficient Implementation of Collective Extended Producer Responsibility Legislation Luyi Gui H. Milton Stewart School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA 30332, luyi.gui@gatech.edu Atalay Atasu Scheller College of Business, Georgia Institute of Technology, Atlanta, GA 30308, atalay.atasu@mgt.gatech.edu ¨ Ozlem Ergun H. Milton Stewart School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA 30332, oergun@isye.gatech.edu L. Beril Toktay Scheller College of Business, Georgia Institute of Technology, Atlanta, GA 30308, beril.toktay@mgt.gatech.edu Extended Producer Responsibility (EPR) is a policy tool that holds producers financially responsible for the post-use collection, recycling and disposal of their products. EPR implementations are typically collective - a large collection and recycling network (CRN) handles multiple producers’ products in order to benefit from scale and scope economies. The total cost is then allocated to producers based on metrics such as their return shares by weight. Such weight-based proportional allocation mechanisms do not consider the synergies inherent in resource sharing in CRNs, and are often criticized in practice for not taking into account the heterogeneity in the costs imposed by different producers’ products. The consequence is cost allocations that impose higher costs on certain producer groups than they should be accountable for. This may lead some producers to break away from existing collective systems, resulting in fragmented systems with higher total cost. Yet cost efficiency is a key legislative and producer concern. To address this concern, this paper develops cost allocation mechanisms that induce system-wide participation in the collective system and maximize cost efficiency. The cost allocations we propose are presented as adjustments to the widely-used return share method, and include the weighing of return shares based on processing costs and the rewarding of valuable capacity contributions to the collective system. We validate our theoretical results using Washington state EPR implementation data and provide insights as to how these mechanisms can be implemented in practice and the added economic value to be obtained by their implementation. Key words : Environment, Regulation, Extended Producer Responsibility, Recycling 1. Introduction Extended Producer Responsibility (EPR) is a policy tool that holds producers financially respon- sible for the post-use collection, transportation and processing (i.e., dismantling, shredding and/or recycling) of their products (Lifset 1993, Lindhqvist 2000). Following its adoption in Europe 1