CERN’s Large Hadron Collider (LHC) entered the so-called Long Shutdown 2 (LS2) period in 2019. During LS2, the accelerator and the experiments are performing various improvements for the upcoming data-taking period, namely Run 3, which is expected to start in 2022. The ATLAS Software and Computing (S&C) community took this opportunity to undertake a set of major developments with the main goal of upgrading the ATLAS software infrastructure, Athena, to be multithreaded. In this talk, we will discuss the ATLAS S&C efforts towards Run 3 and Argonne’s involvement/leadership in this area.