In recent years, considerable effort has been devoted to the study of unsteady flows over the surface of many different vehicles—aircraft, launch vehicles, underwater craft, etc. The fluctuating pressures resulting from unsteady flows can be an important source of vibration and sound and, thus, significantly affect the performance and environments of these vehicles. Fluctuating pressures may arise from several modes of disturbances; however, they are most often introduced by the passage of turbulence over the external surface. Particular phenomena, which can be of significance in various circumstances, include attached boundary layers, separated boundary layers, oscillating shock waves (often referred to as shock-boundary layer interaction), protuberance flows, jet impingement, cavity response phenomena, and base or wake flow. Many of the phenomena above involve forms of turbulent separated boundary layer flows, and the paper is centered around a description of these. The extensions of the available data to unusual geometries, such as space shuttle, will be discussed and examples of the accuracy fo such extrapolation shown. One of the principal problem areas for aircraft and space vehicles is in the transonic speed range, and a major portion of the paper will be devoted to a discussion of the transonic fluctuating pressure environments. Based on test results from many sources, prediction methods for the various unsteady flow environments are suggested. Key features of the present paper are the bringing together of data from disparate sources, combining the results to show general trends for the various unsteady flow phenomena, and, based on the combined results, the development of prediction methods.