Using low temperature above‐ and below‐gap excitation of light induced electron spin resonance (LESR) large densities (≳1017cm−3) of charged midgap states are shown to be associated with the interfaces and/or surfaces of a‐Si:H films. In all cases (films of 5, 10 and 15 &mgr;m thicknesses) the below‐gap LESR produces the same asymmetry in the intensities of the electron and hole lines as we reported earlier, and the induced spin densities scale with the number of interfaces within ±15%. When considered as bulk spin densities, the results vary by more than a factor of three.