What is the trainer's responsibility versus the rider's responsibility in dressage lessons?

The division of responsibility between trainer and rider in dressage lessons is a relationship that functions best when both parties understand clearly what they are responsible for and commit to fulfilling those responsibilities without expecting the other party to compensate for their specific obligations. The trainer's primary responsibilities include providing accurate observation of what is happening between horse and rider, identifying the most productive things to work on at each stage of development, communicating instruction clearly enough that the rider can understand and attempt to implement it, adjusting the lesson's direction based on what the horse and rider show rather than following a fixed plan regardless of what is actually happening, and maintaining an environment of respect and genuine encouragement that supports the rider's development. The rider's primary responsibilities include practicing the specific homework assigned between lessons with genuine focus and effort rather than simply riding without specific developmental intention, arriving at lessons prepared — horse tacked, horse appropriately warmed up or ready to warm up, specific questions from the previous lesson ready to discuss — and being honest with the trainer about what happened between lessons, what felt difficult, and what questions arose. The responsibility for the horse's training and welfare is shared: the trainer observes and directs the training approach, but the rider implements it in daily independent riding, and the quality of the horse's development reflects both the quality of the trainer's instruction and the quality of the rider's implementation of that instruction. A common source of training relationship frustration occurs when riders expect the trainer to produce progress that only the rider's between-lesson work can produce, or when trainers assume that riders are implementing their instruction accurately when a specific check-in about what the between-lesson work actually looked like would reveal significant deviations from what was intended.