A pelham bit is a type of bit used when riding a horse. It has elements of both a curb bit and a snaffle bit. In this respect a pelham bit functions similar to a double bridle, and like a double bridle it normally has "double" reins: a set of curb reins and a set of snaffle reins. Because it has a bit shank and can exert curb-style pressure on the horse, it is considered a curb bit. Like all curb bits, a pelham bit has a mouthpiece, shanks with both purchase and lever arms, a ring for rein attachment at the bottom of the shank, and a curb chain. But like a snaffle bit, a pelham bit also has a bit ring on either side of the mouthpiece. Like some curb bits, a pelham bit usually has "loose" shanks - hinged at the mouthpiece in the same way that the rings of a snaffle bit are hinged. When two sets of reins are used, the snaffle rein generally is wider, to help distinguish it from the curb. A "cowboy pelham" is a western style of loose-jawed curb bit with additional rings at the mouthpiece allowing a second set of reins to be added.

The bit is an item of a horse's tack. It usually refers to the assembly of components that contacts and controls the horse's mouth, and includes the shanks, rings, cheekpads and mullen, all described here below, but it also sometimes simply refers to the mullen, the piece that fits inside the horse's mouth. The mullen extends across the horse's mouth and rests on the bars, the region between the incisors and molars where there are no teeth. The bit is located on the horse's head by the headstall, and which has itself several components to allow the most comfortable adjustment of bit location and control.