This article develops criteria for the selection, professional development, and assessment of cooperating teachers through four "notions." These notions suggest that cooperating teachers might (1) possess knowledge of educational theory and practice; (2) understand the importance of context in education; (3) understand narrative's role in the process of learning to teach; and (4) critically reflect on teaching practice. We explore these notions as qualities that may guide cooperating teachers' work in facilitating student teachers' development. We discuss specific ideas and strategies for mentoring and modeling within various theoretical frameworks and selected research that supports each notion. Throughout the article, we outline policy and practice implications for music teacher preparation programs, including aligning them with current accreditation standards and assessments.