Regular and meaningful opportunities for independent scientific input to global plastics treaty (GPT) negotiations and subsequent implementation is critical to support member states in making science-based decisions, to agree upon common priorities, and to ensure the treaty is comprehensive, credible, just, and effective. Delivering the ambition mandated by UNEA 5/14 will require independent evidence spanning the full life cycle of plastics including feedstock extraction, product design and innovation, as well as consumption, waste management, pollution prevention, and safe and sustainable removal of legacy plastics. The document from the Scientists' Coalition summarises some examples of how independent scientific knowledge can help identify practical pathways to advance negotiations.