The objective of the project was to provide a platform for experts to discuss the operationalisation of international market-based cooperation under Article 6.2 and 6.4 of the Paris Agreement. Perspectives Climate Resarch (PCR) chaired this working group and organised regular workshops, meetings and side events. In addition, PCR prepared publications on issue-specific matters to faciliate the discussions among the carbon market experts. The publications focused on the robust operationalisation of Article 6 rules, closely following the Article 6 negotiations. Publications focused for example on the nature of and interlinkages between Article 6 registries, the methodological operationalisation of the Article 6.4 mechanism and the authorisation of Article 6 credits. According to the working group’s mandate, many publications explored the development of upscaled crediting approaches including sectorial and policy crediting. Other outputs included submissions to the Supervisory Body of the Article 6.4 mechanism and presentations at international climate conferences or carbon market specific events.