The recycling industry has made significant strides toward a closed loop material system in which the materials that make up new products today will become the raw material used to manufacture products in the future. However, contamination in some sources of recycled content raw material (“feedstock”) contain potentially toxic substances that can devalue feedstocks, impede growth of recycling markets, and harm human and environmental health. Since May 2014, the Healthy Building Network, in collaboration with StopWaste and the San Francisco Department of Environment, has been evaluating 11 common post-consumer recycled-content feedstocks used in the manufacturing of building products. This paper is a distillation of that larger effort, and provides analysis on two major feedstocks found in building products: recycled PVC and glass cullet. This research partnership seeks to provide manufacturers, purchasers, government agencies, and the recycling industry with recommendations for optimizing the use of recycled content feedstocks in building products in order to increase their value, marketability and safety. This report was prepared in support of a research session at the 2015 Greenbuild conference in Washington, DC.