Experimental results are presented in the form of schlieren and interferometer photographs showing the interaction of oblique shocks with laminar and turbulent boundary layers on a flat plate in a supersonic stream. The effects of variations in shock intensity and boundary-layer thickness were studied through a Mach number range of 2.0 to 2.5. A greater variety of shock boundary-layer interactions was discovered than had hitherto been suspected. The nature of the interaction was found not to be solely dependent upon whether the boundary layer is laminar or turbulent. A laminar layer proved to be more greatly affected by an incident oblique shock than a turbulent layer. With relatively intense shocks the boundary layer was influenced far upstream of the point of incidence. Injection of a high-speed air stream into a turbulent boundary layer altered significantly the manner of reflection of an incident shock.