Excerpts from the report Introduction: The trend in poultry processing toward centralization and production of ready-to-cook-or-serve products has placed increasing emphasis on waste disposal and recovery of byproducts. Some of this centralization has resulted from building high-capacity processing plants to take advantage of mass production methods, but a great part has resulted from concentration of plants within certain areas. While this centralization has intensified the problem of disposal of poultry wastes, it has been at the same time a strong factor in the development of poultry byproducts, because the amount of waste has been sufficient to attract rendering concern. The bulletin is presented in two parts. Part I deals primarily with the effects of processing variables on the chemical and physical properties and is based largely on work conducted at Western Utilization Research and Development Division, U.S. Department of Agriculture. Part II is concerned with the effects of the same variables on nutritional properties and with overall nutritional evaluation. It was prepared at Ohio State University and is based in part on work conducted there and at Clemson Agricultural College.