Reins are straps that run from a Bridle or harness to the hands of a Driver, Rider or Trainer. They are the principal channel of directional communication in most Pony Play driving and dressage work, supplemented by voice and, where appropriate, the seat.

Rein work in Pony Play is adapted directly from equestrian tradition, with communities emphasising sensitive rather than heavy handling.

Rein technique is a skill developed by both Pony and Driver. Communities that emphasise driving often include rein handling in their training standards.