Horse Trials, also known as "Eventing," are competitions held in three phases. The same horse and rider ride tests in dressage (a precision ride in a flat arena), show jumping (a round over eight or ten fences with rails that knock down), and finally a ride cross-country for one to two miles, while jumping over fences that don't knock down.

Originally, the sport was a contest between cavalry riders to test the horse and rider's ability, stamina, and training for combat. Now, civilians do it for fun.

Riders and horses compete with each other at a skill level where they are comfortable. The lowest fences and the least demanding dressage tests are at the beginner novice level, intended for those competitors who are just starting out. More difficult tests are offered at the novice, training, preliminary, intermediate, and advanced levels.

The intermediate level is the highest degree of competition offered at Greenwood Farm, but international events such as the Olympic Games are at the "advanced" level. You may recall the World Games in Spain the summer of 2002, when the United States team won the gold medal. Greenwood Farm's course designer, John Williams of Virginia, scored the highest individual score of all competitors on the cross-country phase.