This dissertation aimed to better understand how violin and viola private instructors teach Mental Practice in their studios, investigating different approaches on how to apply and teach auditory, motor, and visual imagery, score study, and auditory modeling, as well as its benefits. This research was divided into two different stages. In the first stage, the researcher conducted interviews (n = 19) and collected questionnaire responses (n = 14) from 33 upper-string instructors teaching at the pre-college and collegiate levels in the US. This research stage was based on the grounded theory approach since there was not much research linking mental practice with upper string teachings and how it can be applied to instruction. For the second stage of the research project, the researcher tracked their practice while applying many of the techniques learned through the interviews and questionnaires. This second stage resulted in an autoethnography narrative. The data from both stages of the research culminated in a guide on how upper-string instructors can teach mental practice to their students. Through this research, it was perceived that the understanding of mental practice among the participants was much broader than anticipated. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]