AQ‐switched ruby laser was used to study both reversible and permanent changes in the electrical conductivity of partially compensatedn‐type andp‐type hydrogenated amorphous silicon (a‐Si:H). This method of illumination provides an accelerated test of the magnitude of reversible photoinduced changes (known as the Staebler–Wronski effect) if the laser beam energy is insufficient to produce gross structural alterations in the samples. Compensated films are less susceptible to Staebler–Wronski changes than are single doped films. At energy densities above about 0.2 J cm−2, recrystallization of these thin films occurs, to an extent dependent on the energy. Energies above about 1.2 J cm−2produced no further increases of conductivity. The total increase in conductivity over this energy range was 104–105forp‐type films and 103–104forn‐type films giving similar saturated conductivity values for both series of films. There were also large improvements in photosensitivity.