Cascadia began a waste composition study for the City of Seattle in 2007 with the goals of providing statistically significant data on the composition of waste generated from construction and demolition (C&D) activities within the City of Seattle, identifying potentially recyclable materials in the disposed C&D waste stream, and understanding seasonal and strata differences to improve targeted waste diversion programs. For this study, a total of 786 samples were sorted into 67 distinct component categories, such as clean engineered wood or composition roofing. The study generated comparative data associated with Seattle’s previous C&D waste composition study that took place in 1997 and developed a benchmark for continued long-term measurement of the C&D waste stream.