AbstractHigh‐speed video (46,000 frames per second) and lightning‐mapping‐array (LMA) data are correlated to determine three‐dimensional properties of in‐cloud lightning leaders (altitudes ranging from 2.78 to 3.81 km) observed in a rocket‐and‐wire triggered lightning flash. Three positive leaders were observed with speeds ranging from 6.1 × 104 to 1.0 × 105 m/s, one of which branched within the camera frame. The upper branch was then traversed twice by attempted negative leaders propagating toward the main channel to ground (speeds of 2.4 × 106 and 1.1 × 107 m/s). Both attempted negative leaders terminated abruptly at the branch point of the remnant channel. In the remnants of a separate positive leader channel, a bidirectional leader initiated, which resulted in an M component whose luminosity and current were measured at ground. Analysis shows that the luminosity wave associated with the entire M component process (propagating 8.8 km from initiation to ground) is highly dispersive, with calculated group velocities ranging from 1 × 107 to 5 × 107 m/s over the dominant signal bandwidth of DC (0 Hz) to 2 kHz.