SUSY searched at ATLAS and Dark Matter

SUSY models with R-parity conservation provide an excellent candidate for dark Matter, the LSP, and will be searched for with the ATLAS detector at the LHC, based on signatures including missing transverse momentum from undetected neutralinos, multiple jets and leptons or b and tau jets. Based on recent simulation studies, we present the SUSY discovery reach for the first fb-1 of ATLAS data, and studies about techniques used to reconstruct the decays of SUSY particles at the LHC. We further discuss how such measurments can be used to constrain the underlying susy model and thence to extract information about the nature of dark Matter.