The 2002 Clay School on Geometry and String Theory was held at the Isaac Newton Institute for Mathematical Sciences, Cambridge, UK from 24 March - 20 April 2002. It was organized jointly by the organizers of two concurrent workshops at the Newton Institute, one on Higher Dimensional Complex Geometry organized by Alessio Corti, Mark Gross and Miles Reid, and the other on M-theory organized by Robbert Dijkgraaf, Michael Douglas, Jerome Gauntlett and Chris Hull, in collaboration with Arthur Jaffe, then president of the Clay Mathematics Institute