In this chapter, we examine a mentoring-as-induction and professional development model, which we have researched since 2012. Specifically, we discuss what we discovered about the connections between teacher professional development, the induction and support of beginning teachers, the ways in which collaboration within mentorship relationships among teachers helped both mentors and mentees develop professional competencies and dispositions, and how engaging in collaborative inquiry enhanced professional learning for both pre-service and in-service teachers. Given the benefits arising from mentor/mentee relationships and from collaborative inquiry involving student-teacher mentees and cooperating/host teacher mentors, we provide recommendations regarding beginning-teacher induction and mentorship as well as suggestions about the development of practicum/field study as a site for mentorship and collaborative inquiry within initial teacher-education programs.