This paper explores how young girls develop trust in their equine partners for the purposes of competitive equestrian sport. I argue that interspecies trust manifests through interactional trust and system trust. Interactional trust, as reflected in the horse-human relationship, is built through joint action and results in symbolic interaction. System trust is made possible through the equine community; it develops through communication in an effort to reduce complexity and uncertainty in society. To encourage and sustain youth participation in competitive equestrian sports both interactional trust and system trust are necessary.