Do countries gain more by liberalizing trade together than alone? We study the WTO’s 2016 Phase II expansion of the Information Technology Agreement (ITA), which eliminated tariffs on products covering roughly 12% of world goods trade. Using triple-difference structural gravity, importer–product mar- ket access rose by 4–6%. Decomposition reveals nearly half reflects general- equilibrium coordination spillovers—exceeding contributions from direct tar- iff cuts or reduced policy uncertainty. Exploiting variation in coalition size, spillovers turn positive once participants span about two-thirds of world im- ports—well below the 80% critical-mass benchmark commonly assumed for plurilaterals. Conditional general equilibrium counterfactuals show ITA Phase II reduced members’ import price indexes by 1.4 percentage points on average, peaking near 2.0 percentage points by 2019. Joint liberalization yields benefits beyond the sum of individual actions—evidence of the force of many.