The Cross-Disciplinary Science PhD provides a framework for housing a series of combined PhD programs representing research evolution into cutting-edge areas that cross disciplinary boundaries driven by the demands of current world challenges. The rapid pace of research in these areas requires efficient development of new combined PhD programs, which draw on expertise from different disciplines, and can be developed efficiently under the common framework of the Cross-Disciplinary Science PhD. This framework provides the flexibility for PhD programs that reflect the multidisciplinary nature of the research performed by faculty and students interested in solving challenging problems through cross-disciplinary approaches.