Export restrictions can be problematic if trading partners question either their conformity with international obligations or their possibly unintended negative impacts on others. Regulatory transparency can help. This paper examines how three multilateral environmental agreements (MEAs) incorporate transparency into their regulatory regimes: CITES (endangered species, especially tropical timber), the Basel Convention (hazardous e-waste), and the Kimberley Process (conflict diamonds). All three require producing countries to control exports of sensitive commodities, while allowing (Basel) or requiring consuming countries to control imports. Export and import restrictions are usually intended to affect relative prices, but in these three MEAs the ultimate objective is to limit the negative consequences, whether economic, environmental or societal, associated with improper exploitation of the covered commodities. In each case all trade in the target commodities ought to be covered, no export permits should be issued that do not meet the standards established by the MEA, and no imports should take place without the appropriate documentation. In order to have a consistent comparative basis for assessing the contribution of regulatory transparency to the success of these regimes, we use an analytic framework based on three major transparency principles: publication of the rules (the “right to know”); peer review by governments (monitoring and surveillance); and public engagement (reporting on results, and a role for non-governmental organisations, NGOs). The paper concludes with some observations about characteristics that appear to make transparency more or less effective.