Minecraft wiki entry for Horse, associated text: A player mounts a horse by pressing use on it with an empty hand, or while holding an object that cannot be used on a horse. A player tames an adult horse by repeatedly mounting it until the horse stops bucking off the player. Taming depends on the horse's "temper". Horses begin with a temper of 0 out of 100. When a player first mounts the horse, a random taming threshold 0–99 is chosen. The horse becomes tame if the temper exceeds this threshold. Otherwise, the player is bucked off and the temper is increased by 5, to be compared against the threshold the next time the player mounts the horse. Temper can also be increased by feeding the horse.