How do I teach a horse to side pass?

The side pass is a movement in which the horse travels directly sideways with no forward motion, crossing its legs as it moves laterally. It is useful for opening gates from horseback, positioning precisely in competition patterns, and developing the horse's suppleness and responsiveness to independent leg aids. Many riders attempt to teach the side pass before establishing the building blocks that make it possible, which leads to frustration on both ends of the reins. Done in the correct sequence, however, most horses learn a basic side pass within a handful of sessions. The foundational skill the horse must have before a side pass is introduced is a reliable leg yield. In the leg yield the horse moves both forward and sideways, which is physically easier than pure lateral movement because the forward component carries the horse through the crossing step. A horse that cannot leg yield confidently from both legs has not yet developed the understanding of moving away from leg pressure that the side pass requires. Establishing the leg yield first shortens the side pass learning process considerably. The transition from leg yield to side pass involves gradually reducing the forward component while maintaining the sideways movement. Begin a leg yield along the rail and slowly close the forward opening with a combination of wall and rein, asking the horse to continue moving sideways without the option of moving forward into open space. The fence helps significantly in the early stages because it prevents the horse from moving forward and allows the rider to focus entirely on generating sideways movement. Once the horse understands the concept in one direction along a fence, practice in open space and then in both directions. Horses are almost always more fluid in one direction than the other, and the stiffer direction deserves more quiet, patient work to develop equal suppleness. The side pass should always feel effortless and calm — a horse that rushes or braces through the movement is showing tension that needs to be addressed before the movement is refined.