The objective of this proposal is to organise a high-level multidisciplinary Euro Summer School on DNA and Chromosomes. A full understanding of the structure and functions of DNA and chromosomes requires a multidisciplinary approach. This field is attracting an increasing number of researchers coming from various disciplines. Computer scientists for instance build DNA computers; mathematicians study DNA topology, and polymer physicists take advantage the exceptional polymeric properties of DNA. On the other hand, there is a growing understanding among molecular biologists that biology will in the future benefit of the knowledge accumulated in physics and in physical chemistry. Finally, fundamental questions in molecular biology of the nucleus lead on to physical questions. This multidisciplinary approach, which has led to important results in the past, is expected to have a growing impact in the next decade. Indeed, recent years have witnessed a burst of novel experimental tools to probe structure and dynamics of DNA molecule in vitro and in vivo.