I. Capacity building for emissions trading: Concept and priorities Several contributions to this issue of the Carbon & Climate Law Review have illustrated current efforts to introduce emissions trading systems in the developing world. Overall, this is a welcome trend, as it shows that carbon markets are successfully incentivizing more robust mitigation efforts in countries with the fastest growth in greenhouse gas emissions. Given that any meaningful action on climate change will necessitate allocation of scarce resources among many competing aims, the flexibility and efficiency gains offered by a marketbased approach may indeed be critical for any prospect of avoiding dangerous anthropogenic interference with the global climate system. It is thus readily apparent that ensuring the integrity of these emissions trading systems will become vitally important far beyond the national boundaries of the countries that introduce them.