A trailer jack support comprises a receptacle for receiving a jack post of a trailer jack and a mechanism such as an insert therein for limiting the depth of insertion of the jack post into the receptacle. As a result, the jack post engages the insert with a more limited extension of the jack post. Also, if there is a significant distance between the ground and jack, for example if the trailer happens to be positioned above a depression in the ground, the jack post may not be able to be extended sufficiently to support the jack. By adjusting the elevation of an insert, a trailer jack support in accordance with this disclosure can reduce the extent to which a jack post needs to be extended to accommodate these varying ground conditions.