The Open Debate of this issue examines the central role of materials in shaping circular design practices and steering sustainable transitions. Positioned at the intersections of Transition Design, Advanced Design, and Circular Design, materials are treated not as passive inputs but as co-evolving actors that influence processes, supply chains, and cultural imaginaries. Drawing on theoretical perspectives and international cases, the contributions explore how innovative approaches to material design can regenerate resources, increase transparency via digital and AI-based tools, enable collaborative supply chains, and cultivate new aesthetic and ethical values. By addressing materials as agents of change, design emerges as a catalyst for systemic and cultural transformation amid current environmental and social crises. Across the section, four operational implications for practice converge, outlining an integrated framework for action. Flaviano Celaschi
