On 20 February 2012, the U.S. and Mexico signed the Agreement between the United Mexican States and the United States of America Concerning Transboundary Hydrocarbon Reservoirs in the Gulf of Mexico (the 'Agreement').(1) This Agreement while not in force yet(2)-is the first serious governmental attempt(3) to establish a set of rules governing the exploitation of oil and gas reservoirs in what both countries see as a real possibility in the Gulf of Mexico: shared deposits. The Agreement provides for the joint, efficient and equitable exploitation of such reservoirs.(4) This article outlines the main features of the exploitation of transboundary hydrocarbon reservoirs provided for in the Agreement, new possibilities for cooperation and business development between oil and gas companies(5) along the maritime boundaries whether or not transboundary hydrocarbon reservoirs are in place and whether companies really need these provisions, or whether exploration of shared deposits could successfully take place without the Agreement.