The last decade has seen a proliferation of mentoring programs that provide high-school students authentic research experiences. Such programs expose students to front-line research, equip them with basic research skills (including coding skills), and introduce them to scientist role models. Mentors in such programs range from undergraduate students to faculty members. Here, I describe the founding and first two years of operation of the Harvard Science Research Mentoring Program (SRMP). This program specifically recruits advanced graduate students and postdoctoral scholars to serve as mentors. By mentoring high-school students over a long timescale (September to May), early-career scientists gain hands-on experience in the skills required to advise students|skills that are often required of them in future academic positions yet seldom taught by academic institutions. Finally, I invite directors of existing and prospective SRMPs to join the Global SPHERE Network, through which directors of SRMPs around the world can share their experiences, best practices, and questions.