Horses'' fear reactions can lead to problems such as accidents and injuries to horse and rider. The objective of this work was to identify factors influencing fear in riding horses. Results revealed that riders could induce nervousness in the horse by unconsciously communicating their own nervousness. Riding style also had immediate consequences for fear reactivity in horses: When horses were ridden in the more coercive, and to the horses aversive, Rollkur style, they showed stronger fear than when they were ridden in a regular riding style. In contrast, horses of genetic show-jumping lines exhibited weaker fear reactions than horses of dressage lines regardless of their longterm training experience. It was concluded that fear reactivity in horses could be reduced: 1) by genetically selecting against fear reactivity in horses, 2) by employing less coercive riding techniques and 3) potentially by developing and training specific techniques, such as muscle relaxation, that allow riders to interrupt the exchange of nervousness between rider and horse. Ultimately these approaches could aid to improve safety and welfare of both horses and riders.