ESnet is the high-performance network serving thousands of U.S. Department of Energy scientists and collaborators worldwide. Over the past few years, ESnet and Internet2 have shared a common technical vision for the evolution of dynamically delivered network capabilities for future scientific research. In August 2006, the two networking organizations announced a partnership to develop and deploy the next generation of ESnet using the new Internet2 Network optical infrastructure. Thus, the ESnet and the Internet2 communities are working together toward their mutual need for the development of a scalable, sustainable, high-performance network backbone that connects researchers and scholars at Internet2 member institutions with scientists at the Department of Energy.