Purpose: Special and differential treatment (SDT) in the World Trade Organisation (WTO) has failed to integrate developing countries into the international trading system, as contemplated by the WTO Agreement, itself. This paper aims to interrogate the current application of SDT by WTO members as the possible undermining factor for SDT not delivering on its objective. Design/methodology/approach: The research uses a qualitative legal methodology. This study conducts desk analysis of primary legal materials and existing literature to assess current reflections of SDT and draw lessons for reforms in the WTO. Findings: From interrogating current SDT practice in the WTO and a comparative analysis with a similar differential treatment under the Montreal Protocol, this paper finds that indeed, the problem lies in the current approach to SDT application in the WTO. This study finds that the existing absence of eligibility criteria for determining access to SDT by countries is the core reason for the abuse and sub-optimal outcome from its application. Originality/value: While making a case for a rules-based approach to differentiation in the WTO, this paper proposes a unique methodology for differentiating between developing countries for SDT, including the use of a composite indicator to ensure that indicators that are used sufficiently reflect their heterogeneous needs. Drawing inspiration from Gonzalez et al. (2011a), this study introduces an adaptation for selecting a threshold for graduation. Specifically, the proposal on the value of the standard deviation of countries from the weighted mean of the composite indicator as the threshold for graduating countries from SDT is novel.