Transition-to-Success Mentoring Act This bill reauthorizes educational programs that assist at-risk middle school students. The bill establishes a transition-to-success mentoring program requiring the Department of Education to award grants to local educational agencies or certain community-based nonprofit organizations to provide school-based mentoring programs and assist at-risk students in transitioning from middle to high school. Grantees must assign each at-risk student in his or her middle school a success coach who creates a plan of success for the student and serves as the student's advocate between the student's parents and teachers and in exploring higher education and career opportunities.