Global industry has made progress toward a world in which more efficient use of resources, including recycling, helps to reduce impacts on the natural systems that support life. However, contamination of recycled-content raw material with potentially toxic substances reduces feedstock value, impedes growth of recycling rates, and can endanger human and environmental health. This paper provides findings and recommendations about how progress in resource use efficiency and recycling can occur along with the production of healthier building products. This paper is based on the review of eleven common recycled-content feedstocks used to manufacture building materials that are sold in California’s San Francisco Bay Area. It provides manufacturers and purchasers of building products, government agencies, and the recycling industry with recommendations for optimizing recycled-content feedstocks in building products to increase their value, marketability and safety.