Assessments of the behavior of ridden horses form the basis of performance evaluation. The purpose of any performance being evaluated will determine the factors considered important, those indicative of 'poor' performance and what makes a successful equine athlete. Currently there is no consistent objective means of assessing ridden horse behavior and inevitably, given the different equestrian disciplines, the likelihood of a universal standard of good and bad performance is remote. Nevertheless, in order to protect the welfare of the ridden horse regardless of its specific role, we should strive for consensus on an objective means of identifying behavioral signs indicative of mental state. Current technological developments enable objective evaluation of movement patterns, but many aspects of the assessment of ridden behavior still rely on subjective judgement. The development of a list of behaviors exhibited by ridden horses, a ridden horse ethogram, will facilitate recording of observable behavioral events. However, without objective evidence of the relevance of these behavioral events, such a resource has limited value. The aim of this review is to investigate potential sources of such evidence and relate these to the assessment of ridden horse behavior. The current and potential contribution that further objective measures can make in this process is evaluated. We believe that the only way to improve the welfare of the ridden horse is by objectively identifying behavioral signs that indicate that the horse is either comfortable or uncomfortable with the activity in which it is participating. Once there is clear evidence to support this, appropriate adaptation of performance criteria in all disciplines can proceed along with alignment in training systems that ensures a mutually positive experience for both horse and human partners.