The multilateral trading system has continuously evolved to take account of the changing nature of non-tariff barriers (NTBs). This paper contrasts GATT terminology with the definitions frequently found in the literature and describes the multilateral tools that were used in the past to identify NTBs. The latter includes an overview of inventories based on ‘reverse’ notifications and, more recently, the ‘specific trade concerns’ raised in WTO Committees. The paper also looks at the provisions cited by complainants in more than 60 years of multilateral disputes as a proxy for identifying the most relevant NTBs affecting trade in goods, as well as the manner in which they have evolved over time. It concludes that agricultural and non-agricultural products face very different NTBs, and observes that while disputes involving agricultural products are increasingly about ‘behind-the-border’ NTBs, those involving non-agricultural or mixed products are not. Finally, the paper proposes the establishment of a new multilateral instrument to collect and classify information on NTBs based on specific trade concerns raised in the context of the ordinary WTO bodies.