The cognitive approach considers that learning a motor skill results in the acquisition and the memorization of an internal representation of the movement (often conceptualized as a motor schema) which is used to build a motor program and define a sensory reference of the movement before its execution. This acquisition is allowed by the processing of movement related information (sensory feedback) and information about movement outcome (knowledge of results) leading to an improvement of the efficiency of sensory-motor loops involved in movement control. Motor learning also implicates higher cognitive processes, especially when the conditions of practice necessitate a cognitive effort, when the learner is provided with verbal instructions or mentally rehearses the motor action to be learned. Generally, the involvement of cognitive processes results in beneficial effects on motor learning but, in some cases, they can interfere with sensory-motor processes rendering more difficult the acquisition and memorization of the skill. We will examine these complex relationships between sensory-motor processes and cognition during motor skill learning.