Teacher design teams (TDTs) are professional learning communities in which teachers collaborate to (re)design innovative educational materials. When appropriately supported, TDT work stimulates the explication and use of pedagogical content knowledge, thus providing important opportunities for teachers to learn from one another. However, TDT coaches struggle to provide adequate support, largely because this concerns not only vertical leadership through the structure, clarity and quality of the team process, but also the creation of an environment in which leadership is distributed among participants. In this conceptual article, we draw on research literature from teacher design teams and team leadership to conceptualize guidelines for TDT coaches. Specifically, we address the question: How can TDT coaches support professional learning and team effectiveness? To support TDT coaches in the translation of research-based guidelines to daily practice, a concrete routine is provided and examples of enactment are given. Alignment with other design team routines is discussed, along with considerations related to the needs and perspectives of both TDT coaches and participants alike.