The negotiations on market and non-market approaches to international cooperation under Article 6 of the Paris Agreement will take centre stage at COP 25 in Madrid. Our policy paper “Negotiating cooperation under Article 6 of the Paris Agreement” explains the crunch issues in Article 6 negotiations in generally accessible language and simple graphics. It was elaborated together with Benito Müller and the European Capacity Building Initiative (ecbi) and benefitted from inputs from Article 6 negotiators. The paper sheds light on the key differences between negotiating Parties on the eve of COP25 in Madrid. Understanding the issues and Party positions is a key step to identify solutions in these highly political and technically complex negotiations.