Steady small disturbances in a compressible boundary layer flow past a slightly wavy swept wall are analyzed including the effects of compressibility, heat transfer and possible ablative response of the wall surface. The theory indicates that the non-uniform flow in the boundary layer can produce a subsonic wall pressure signature even when the local inviscid flow is moderately supersonic. For an ablating surface at high heat transfer rates, it is shown that the interaction of the gas dynamic and surface material disturbances can lead to a condition of "resonance" at a certain critical ratio of boundary layer thickness to surface wavelength. The results of some recent wind tunnel studies of turbulent boundary layer flows past a nonablating wavy wall in the Mach number range .8 < Me < 1.8 are also shown to corroborate theoretical predictions of both pressure and temperature perturbations.