A turbulent spot was created artificially in a transitional boundary layer by means of a point disturbance which was made as reproducible as possible. Single‐probe hot‐wire measurements of the streamwise velocity component were used to study the structure of the disturbance prior to its breakdown into a spot. The ’’incipient spot’’ in this experiment is found to be highly evolutionary, its length increasing by almost 100% during transit past a fixed location. The contour of the incipient spot, when projected on a plane parallel to the wall, is arrowheaded in shape with an apex which is considerably sharper than that of a turbulent spot. In the plane of symmetry, rapid fluctuations are observed far from the wall; closer to the wall, a velocity excess occurs and regions of streamwise momentum defect and excess develop alternately in the spanwise direction. Time history at a fixed streamwise location shows that the central excess region is crossed by a ’’defect bridge’’ connecting the downstream ends of the adjacent defect regions. The incipient spots in this experiment propagate considerably faster than the three‐dimensional wave packets, which have been investigated by others who applied the same, yet much weaker, disturbance source.