The purpose of this study was to develop an effective method for trailer loading horses based on the principles of positive reinforcement. Target training and shaping were used to teach trailer loading behavior in a natural setting. Five AQHA mares were selected for this program. All five had been loaded before through the use of punishment. A two-horse trailer was used. Approximations to loading and inappropriate behaviors were the dependent variables. When intervention started the target was moved to various locations inside the trailer. Subjects started training on the left side of the trailer. After a subject was loading in the left side they were moved to the right side, then to loading half on the right and half on the left, then they were loaded by a different trainer, and into a different trailer. For one subject a limited hold was utilized, as well as a companion horse.