How can I train my horse to drop its head under saddle?

Teaching a horse to lower his head on cue under saddle — to release through the poll and jaw and carry his head in a lower more relaxed position in response to a specific rein or seat aid — is one of the most commonly sought training outcomes in western riding and one that is simultaneously straightforward in principle and easily corrupted in practice. The straightforward version produces a horse that carries his head at an appropriate relaxed height as a consequence of genuine relaxation and self-carriage. The corrupted version produces a horse that carries his head low because he has been mechanically forced into that position — which looks similar from a distance but feels and functions entirely differently under saddle. The correct foundation for head lowering begins on the ground rather than under saddle. Teaching the horse to lower his head in response to poll pressure applied by the hand — placing one hand gently on the poll and applying light downward pressure, then releasing the instant the head drops even slightly — establishes the pressure-and-release communication that the under-saddle head lowering aid translates directly from. A horse that will drop his head to the ground in response to light hand pressure on the poll has learned the foundational communication that the rein aid for head lowering simply replicates from the saddle. Under saddle, the most effective aid for teaching head lowering is a light steady downward and slightly forward feel on both reins simultaneously — not a backward pull, which raises the head rather than lowering it, but a following feel that asks the horse to reach forward and down into the contact. A backward pull on both reins creates poll pressure that pushes the head up and the nose out. A forward-down feel that follows the horse's mouth encourages the horse to stretch forward and down into the rein, which produces the relaxation through the topline that genuine head lowering reflects. Rewarding the search for the lower position — through immediate rein softening the moment the horse begins to lower his head — is the specific training mechanism that teaches the horse that the lower position produces relief. The reward must be immediate and must be a genuine softening rather than a slight reduction in pressure. The horse that discovers that dropping his head to the desired position produces a complete release will develop the full response. Transitions are the most powerful tool for developing consistent head carriage at the correct height, because each transition requires the horse to reorganize his balance and his topline. A horse whose topline is correct — genuinely relaxed and swinging through the back with the hind legs engaged — will naturally carry his head at an appropriate height without requiring specific head-lowering work, because the head position is an expression of the topline quality rather than an independent variable that can be trained separately from it.