Illumination devices characterized in that they include one or more light sources disposed within a housing attached to a clip adapted to receive a portion of a wearer's headdress, for example a chin strap or bill of a cap. An upper surface of the clip may be shaped to be worn under the wearer's chin and may also include a groove adapted to facilitate attachment of the illumination device to nylon or other strap-like webbing. One or more of the light sources is operable by a switch mounted on an opposite side of the housing from the clip when the clip is in a closed position, that is, when the clip rests on an upper surface of the housing. In addition to light sources, the illumination device may further include one or more imaging devices, e.g., a camera, and/or audio communication devices, e.g., a microphone.