The chapters in this volume explore different ways that co-design of curriculum can make learning more relevant to teachers and students, support teacher learning, and promote the sustainability of particular innovations. Many of the chapters conclude that in fact, there is great potential for co-design to support each of these aims. Co-design, for example, can promote teacher ownership over the curriculum, including when reform goals that guide development are set by policy makers who are far from the classroom (Westbroek, de Vries, Walraven, Handelzalts, & McKenney, this volume). Co-design can facilitate "curriculum renewal" among inservice teachers-that is, a transformation in teachers' goals for students and pedagogical approaches. For pre-service teachers, co-design can support integration of technology into teaching (Agyei & Kafyulilo, this volume; Alayyar & Fisser, this volume). Further, teachers can continue to learn from the implementation process (Huizinga, Nieveen, & Handelzalts, this volume). Finally, there is some evidence presented in this volume that co-design facilitates sustainability by creating processes for ongoing curriculum renewal. But the chapters in this volume also explore limitations or boundary conditions under which co-design can produce these positive outcomes. For one, the organizational conditions matter. Teachers need time not just to develop curriculum, but also to learn the skills of curriculum design and to implement and evaluate it using a cycle of iterative testing and revision (Albashiry, this volume; Handelzalts, Nieveen, & Van den Akker, this volume). And since most curriculum design projects require coordination among actors at different levels of systems and within organization, systems of formal and informal communication to ensure coherence are needed