Mentoring is a highly recognized and accepted strategy for attracting, developing, and sustaining leaders across the education sector and beyond. It helps accelerate learning, reduce isolation, and increase the confidence and skill of newly appointed school leaders. It can also be a powerful learning and growth opportunity for the experienced principals and vice-principals who become mentors. This article discusses a unique MentoringCoaching program developed by the Ontario Principals' Council (OPC), the professional association for public school principals and vice-principals, in partnership with the Ministry of Education and school districts across the province. The MentoringCoaching Program, established in 2008, is grounded in the principles and practices of adult learning. It takes a comprehensive approach to professional growth by facilitating knowledge and skill development within a collaborative community of practice and builds on learning from prior mentoring efforts within the province. It is distinct in its ability to combine mentoring and coaching into one inclusive program. The combination of mentoring and coaching are integral to the success strategy of developing educational leaders throughout the province of Ontario. In just a short time, there has been improved performance of new administrators, additional capacity building, support of system priorities, and access to external ideas and support. There is good reason to believe that the quality of instructional leadership across the system will continue to improve as increasing numbers of aspiring leaders are motivated to grow through MentoringCoaching.