This thesis develops a structured methodology to integrate social sustainability indicators into the Digital Product Passport (DPP). Starting from a systematic literature review and an analysis of corporate sustainability reports, 56 indicators were identified and harmonised. Building on this evidence, the research proposes an original two-level integration model and a final taxonomy designed for digital traceability systems. First, indicators are organised into five macro-categories: Labour and Working Conditions, Human Rights and Governance, Community and Social Impact, Product Integrity and Supply Chain Transparency, and Consumer-related Aspects, derived from a qualitative synthesis of the literature and only conceptually aligned with the European Sustainability Reporting Standards (ESRS).