Elliott H. Lieb, Robert Seiringer, Jakob Yngvason The Ground State Energy and Density of Interacting Bosons in a Trap (28K, LaTex) ABSTRACT. In the theoretical description of recent experiments with dilute Bose gases confined in external potentials the Gross-Pitaevskii equation plays an important role. Its status as an approximation for the quantum mechanical many-body ground state problem has recently been rigorously clarified. A summary of this work is presented here.