It is organised by the National Reined Cow Horse Association in North America, and by the European Reined Cow Horse Association in Europe.

"[4] The other is the cow work, where a single cow is released into the arena and the horse is asked to first hold the cow at one end of the arena (known as "boxing") then run the horse along the rail of the arena, turning it back without the aid of the fence (known as "fencing").

Herd work is most often included in three-year-old futurity and four- and five-year-old derby classes.

[4][5] (The Arabian Horse Association omits the reining work in its breed shows.

[3]) The horse is judged on the ability to control the cow, as well as speed, balance, responsiveness to the rider.