Culturally Responsive Education has been widely proposed as a mechanism to improve the academic achievement of minority and Indigenous populations. Instruction in heritage languages has been shown to produce desirable outcomes both on linguistic and academic measures. However, culturally responsive and immersion instruction faces a number of challenges; among them a lack of materials that (a) reflect and accurately represent ancestral knowledge and worldview, (b) are linguistically appropriate to elementary students, and (c) are aligned with state mandated outcomes in the content areas. In this paper we report on a university-school collaborative project, designed to develop Yup'ik language and cultural materials for elementary level Yup'ik-immersion and Yup'ik/English Dual Language schools in Southwest Alaska. Beginning with an overview of what we view as essential elements contributing to a strong and sustainable immersion program in K-12 education, we then discuss the process of the collaboration and tensions that arose during the course of the materials development project. Finally, we present two books developed as a result of this collaborative process.