Two prototype traversing boundary-layer pitot probes were demonstrated in flight. A motor-operated screw-driven type of probe was used on two jet aircraft for defining boundary layers at profile edge Mach numbers from 0.5 to 2.2. The other type of traversing probe was motor driven through a Scotch yoke mechanism and was operated on several flights of the X-15 airplane. The highest free-stream Mach number reached during this series of flights was 5. 6. The mechanical and electrical features of these probes are described, and photographs and conceptual drawings are included. Problems encountered during the development of the devices are described, and the solutions that were found are explained. Boundary-layer profile data are presented in several forms, and local friction coefficients derived from the profile through a Clauser type of determination are shown.