Turbulent boundary layers were fully developed over either smooth or rough walls. Reynolds numbers based upon boundary layer thickness and freestream velocity are on the order 104. Fluctuating pressures at the boundary were investigated within a local region, where a freestream pressure gradient was applied. The flow reequilibrated to the negative pressure gradient and was self‐preserving, in the region of measurement. With a positive pressure gradient, the flow tended toward separation with increasing downstream distance and was not self‐preserving. Two flush‐mounted microphones provided pressure spectral densities and time‐autocorrelations at single points on the boundary, as well as cross spectra and cross correlations from pairs of points. The influence on wall pressure of roughness is explained in terms of its effects on the mean velocity profile. Fluctuating pressure models, which incorporate a unique dispersion relationc(f) (the phase velocitycis obtained from the cross‐spectral density) are found to be inapplicable to flows with a positive freestream pressure gradient. [Research supported by NSRDC.]