Abstract: A blind fastener assembly is disclosed, which is suitable for use in joint assemblies including advanced composite materials. The fastener assembly includes a pin, an expander, a sleeve, and an expandable washer, each of which have an initial diameter which permit them to pass through a hole in the workpiece. The washer is mounted about the pin shank between the sleeve and a tapered nose portion of the expander. The fastener assembly is inserted in a hole in the workpiece so that the expander head abuts the workpiece. Rotation of the pin causes the sleeve to force the washer to slide over the tapered nose portion of the expander causing it to expand and abut the blind side of the workpiece. In one embodiment of the invention the pin threadably engages the expander, and the head of the pin is positioned on the blind side of the workpiece. The washer is initially seated in a groove in the pin shank.