The interaction of a 10.6‐&mgr;m‐wavelength electromagnetic wave with an independently created overdense plasma has been investigated at incident intensities on either side of the field‐strength conditionVosc/Vth=1. An intensity threshold for transmission of the radiation through the overdense target plasma was observed nearVosc/Vth=1. Temporal behavior of the transmitted radiation pulse was compared to that of the incident pulse over an intensity range (0.1–4) ×1011W/cm2.