The principle of non-discrimination lies at the core of international economic law (IEL). The norm is classically instantiated across IEL in two recurrent principles: national treatment (NT); and most favored nation (MFN). NT prohibits vertical discrimination—where a state affords preferable treatment to its own nationals as compared to foreigners. MFN prohibits horizontal discrimination—where a state treats nationals from one foreign state better (or worse) than nationals from another. These principles are foundational in IEL, and thus both well-known and well-considered. Indeed, until recently, the questions of the day across IEL concerned to what extent international trade and international investment law have moved beyond the non-discrimination paradigm. Yet, we see a renewed and growing importance in these classical norms in the practice of IEL over the past few years—in both treaty-making and dispute resolution. The purpose of this roundtable is to discuss non-discrimination's renewed centrality across IEL, and the extent to which the scope and contours of NT and MFN may be in flux across its varied regimes.