This memorandum summarizes information on refractory materials and composites that was presented at the Thirteenth Meeting of the Refractory Composites Working Group in Seattle, Washington on July 18-20, 1966. The memorandum is based on 34 papers that were presented at the meeting. They are reviewed and discussed briefly within the framework of the following four broad areas: materials technology, process technology, specific hardware applications and tests, and evaluation techniques. Included in the section on materials technology are discussions dealing with bulk refractory materials, coated systems, and fiber-reinforced composites. The section on process technology discusses cladding and general fabrication processes. The specific hardware applications and tests cover rocket-motor components, and cladding of a probe used in the glass industry. The section on evaluation techniques covers thermal testing, and non-destructive testing. (Author).