Measurements of the underlying event with ATLAS

Particle distributions sensitive to the underlying event and multi-parton interactions in proton-proton collisions have been measured with the ATLAS detector at the LHC at 7 TeV centre-of-mass energy. Various complementary measurements are presented, e.g. charged particle multiplicity, charged and inclusive sum transverse momentum densities and mean charged-particle transverse momentum in the regions of each event azimuthally transverse to the hardest jet or Z boson directions. When compared to the predictions of different Monte Carlo models, the data show sensitivity to the modelling of the underlying event.