The 20th International Conference on General Relativity and Gravitation (GR20) and the 10th Amaldi Conference on Gravitational Waves (Amaldi10) which takes place from 7th – 13th July 2013 at Uniwersytet Warszawski, Warsaw, Poland. GR20 is the latest in the series of triennial international conferences held under the auspices of the International Society on General Relativity and Gravitation. This conference series constitutes the principal international meetings for scientists working in all the areas of relativity and gravitation. The Amaldi conferences are held under the auspices of the Gravitational Wave International Committee. Since 1997, they have been held every two years and are regarded as the most important international conferences for the gravitational wave detection community. This time, in Warsaw, GR20 and Amaldi10 are organized as a joint event.

The program of the conference, among many topics, includes: Planck Results, Dark Energy, Formation of the Trapped Surfaces, Dynamics of Asymptotically AdS spacetimes, Gravity and Condensed Matter Correspondence, Numerical Relativity and Its Applications to Astrophysics and High Energy Physics, Neutron Stars, Formation of Supermassive Black Holes, Modified Gravity as Alternatives to Dark Energy or Dark Matter, Cold Atoms for Equivalence Principle Tests and GW Detection, Quantum Fields in Curved Space-time, Higher-Dimensional Spacetimes, Loop Quantum Gravity, Strings and Branes.