Transient electrical conductance measurements have been made on 0.45‐&mgr;m silicon‐on‐sapphire during pulsed laser annealing with 25‐ns ruby irradiation. The photoconductive contribution to the transient current was sufficiently small that the entire melt and resolidification process could be directly observed. The technique yields quantitative measures of melt depths, melting velocities (5–13 m/s), and solidification velocities (2.8–3.3 m/s). Combined with the complementary techniques of time‐resolved reflectivity, energy transmission, and calorimetric energy absorption, transient conductance provides a powerful new diagnostic for investigating melt dynamics.