Retailers are strategically positioned to leverage environmental improvement over product supply chains through actions targeted at suppliers and consumers. Informed by scientific evidence on environmental hotspots and control points across 14 priority product groups, and a review of 25 major European retailers' actions, this paper proposes a framework to guide and assess retailer best practice in supply chain environmental improvement. Commonly used product standards and improvement measures are classified into “basic” or “good” levels of environmental protection. A hierarchy of eight Best Environmental Management Practices (BEMPs) is proposed to systematically identify and improve the most environmentally damaging supply chains across retail assortments. Widespread third party environmental certification is the most transparent and verifiable mechanism of improvement but may not be appropriate for some supply chains. The enforcement of retailer-defined environmental requirements, and supplier improvement programmes based on performance benchmarking and dissemination of better management practices, are alternative BEMPs that may be used in combination with third party certification. Facilitating consumer selection of frontrunner ecological products is a lower priority BEMP owing to the well documented limitations of this approach. From available data, the highest current or credible-target sales shares of products improved according to the highest priority BEMP and environmental protection level were used to derive “benchmarks of excellence” for each of the 14 product groups. The assessment framework is demonstrated through application to three retailers.