This volume of the Perspectives on Mentoring Series explores the role of mentoring in promoting wellbeing of both mentees or proteges and mentors in K-12 school settings. At its core, mentoring is about helping, advising, supporting, and guiding mentees and proteges to gain a wide variety of skills, abilities, and/or attributes. Another outcome of mentoring, less often discussed, is the positive impact it can have on the mental health and wellbeing of both the mentor and mentee. Of particular interest for this edited volume is how mentoring can promote mental health, build resilience, and develop capacity to maintain and sustain emotional, psychological, and social wellbeing for all in the K-12 school settings. The notion of wellbeing, in general, includes both hedonic aspects of feeling good (positive emotions) and eudemonic (conducive to happiness) aspects of living well that entail experiences of positive relationships, meaningfulness in life and work, senses of mastery and personal growth, autonomy, and achievement. This edited volume expands and adds to the existing literature on mentoring in schools, by offering a collection of works that examine the connection between mentorship and wellbeing. This volume includes chapters that describe effective mentoring for wellbeing, detail positive approaches to mentoring youth, offer recommendations for growing the wellbeing of pre-service teachers, early career teachers, and mid-late career teachers, illustrate approaches to growing a community of educators through mentoring and developing teacher leaders as agents of change and facilitators of wellbeing, and discuss studies and models for nurturing and promoting wellbeing among and through school leaders in national and international settings. Through these chapters, authors advocate for greater attention to how to support and nurture wellbeing as central to mentorship efforts in K-12 school settings.