What kind of animal is a horse? Whilst we acknowledge that the idea of ‘nature’ is socio-cultural, in this chapter we explore how horsepeople generally perceive the ‘nature of horses’. Humans may marvel at that powerful icon of ‘wild’ horses, the mustang stallion, running free across the prairies; yet horsepeople often long for a special, unique relationship with a horse. In this chapter, we describe how the concept of the natural horse is far from natural; it is stretched and pulled by ideas around what is wild and tame behaviour and who are wild and domesticated horses. Even though there are ongoing debates in scientific studies and lay practice about how humans should relate to horses, there seems to be a general acceptance that horses are always becoming but never quite fully wild/tame or natural/cultural.