Abstract: The present invention relates to a portable security door stop for dependably holding a door in a closed position again any unauthorized entry which may be quickly and conveniently installed on the inside of the door. The invention provides a door handle engaging yoke which is virtually impossible to dislodge from the door; has a convertible floor engaging member having a plurality of cleats for use of carpet but which are also adaptable to provide a mounting system for an auxiliary resilient block or pad adapted for use on relatively hard floor surfaces; and including an audio-alarm unit closely associated with the yoke which is triggered by even the inward movement of the door against the stop.