The document summarizes an Erasmus+ project that aimed to promote transnational cooperation among CLIL (Content and Language Integrated Learning) teachers. The project involved partnerships between schools and universities in several European countries. It established an online learning platform and open database to facilitate teacher observations, training, and sharing of CLIL teaching materials. Challenges included coordinating partners with different CLIL frameworks and producing new high-quality online content. The resulting EduCLIL MOOC provides CLIL teaching certification upon completion and benefits teachers by increasing access to open resources and an international learning community.