Indexable thread-turning toolholders are used with lathes or CNC turning machines as part of a thread-turning tool system to cut threads on a workpiece. These threading toolholders have a shank that mounts to a compatible machine. They accept a compatible thread-cutting head, which holds the thread-turning inserts. The quick-change design of the toolholder allows heads to be swapped out to different threading, boring, or turning heads while the toolholder remains in the machine. Indexable threading tools require fewer tool changes than solid tools in high-volume metalworking and fabrication applications with high speeds, high feeds, and difficult-to-machine materials.