ABSTRACT Sustainability agreements are at the centre of the debate on the relationship between sustainability and competition law. The European Commission has intervened on the issue by inserting in the new Horizontal Guidelines a specific chapter devoted to them. This paper aims at analyzing the approach adopted by the Commission, with a particular focus on the controversial competitive assessment of sustainability agreements under Article 101(3) TFEU and the “fair share” criterion. The analysis is conducted in consideration of the main relevant insights deriving from a comparison with the initiatives taken at national level by some competition authorities and also provides a quick look at the global scenario, in particular with reference to the US, in order to show some of the divergence among jurisdictions with regard to the antitrust treatment of sustainability agreements between competitors.