OER Knowledge CloudBook ChapterXu, SiminLo, Chung KwanUNESCO published recommendations in 2019 to guide the development of open educational resources (OER) to promote quality and inclusive education. This multiple case study explores the development and adoption of OER and policy guidance on implementing OER in Hong Kong schools. Our goal is to understand the school policies on OER adoption, challenges faced by teachers and school leaders in adopting OER, and their suggestions. Using a qualitative approach, we interviewed teachers and leaders from different schools. By comparing three representative cases, we gained a comprehensive understanding of OER development and adoption. We applied the UNESCO’s recommended framework for discussion, focussing on: (1) ensuring the development, storage, and accessibility of OER; (2) aligning quality assurance procedures; (3) integrating OER into the curriculum; and (4) supporting awareness raising and capacity building. The findings contribute to generating insights to inform the future development and adoption of OER in primary and secondary schools.20252025/07/25EnglishSpringer235-251Hong Konghttps://doi.org/10.1007/978-981-96-2921-3_14978-981-96-2921-3yesOER adoptionpolicyimplementationprimarysecondaryHong Kong, Asia