During the process of conceptualizing the school of which she is the founding principal, Denver Montessori Junior/Senior High School, Katy Myers' driving question was, "What exactly is Montessori high school?" Her answer to this question gets to the heart of the mission of many Montessori high schools. She concluded that her high school must be guided by the principle that "adolescence is the sensitive period for social justice." In presenting how her thinking developed from this point, Myers offers an essential understanding of the work, at both the junior and high school levels, that is centered around empowering adolescents with the tools they need to have the agency to make social change. [This talk was presented at the NAMTA Adolescent Workshop at the AMI/USA Refresher Course, February 17-20, 2017 in Austin, TX.]