Sustainability agreements can generate significant environmental, social and economic benefits, but cooperation between competitors must remain compatible with Article 101 TFEU. The European Commission (the Commission) assesses sustainability agreements under the ordinary Article 101 TFEU framework: an agreement may fall outside Article 101(1) TFEU, may be covered by an applicable block exemption, may require an individual assessment under Article 101(1) TFEU, or, where restrictive, may satisfy the four cumulative conditions of Article 101(3). This Checklist is intended to support an initial legal and compliance assessment. It should be used alongside the relevant chapters of the Horizontal Guidelines, applicable block exemption regulations, sector-specific rules and case-specific legal advice. The assessment is fact-sensitive and should be revisited if the agreement, market conditions or participating businesses materially change. What is the agreement and what sustainability objective does it pursue? The starting point is to identify the cooperation, the parties and the sustainability objective. The Commission defines a sustainability agreement broadly as any horizontal cooperation agreement that pursues a sustainability objective, irrespective of the form of cooperation. In