The cooperating teachers who make the greatest positive impact on interns allow student teachers to make mistakes and learn from them, offer constructive feedback, invest in their student teachers' success, practice current pedagogy in their own classrooms, and remain positive throughout the experience. In this article, the author suggests that mentors need to be aware of some key factors that motivate human beings, and she offers guidelines that should help mentor teachers facilitate the growth of prospective teachers in a way that is humane, logical, and effective.