The interaction between an impinging oblique shock–wave and a laminar boundary layer on a flat plate is investigated using direct numerical simulations. The two–dimensional separation bubble resulting from the shock boundary layer interaction (SBLI) at freestream Mach number of 2.3 for the approach flow is investigated in detail. The flow parameters used for the present investigation match the laboratory conditions in the experiments conducted at the University of Arizona (UA). In addition to the steady flow field calculations, in order to study the linear stability behavior of the separation bubble, the response to low– amplitude disturbances is investigated using linearized Navier Stokes calculations. For comparison, both the development of two–dimensional and three–dimensional (oblique) disturbances are studied with and without the impinging oblique shock. Furthermore, the effects of the shock incidence angle and Reynolds number are also investigated. Finally, three–dimensional direct numerical simulations were performed in order to investigate the laminar-turbulent transition process in the presence of a laminar separation bubble generated by an impinging shock–wave.