An apparatus for stabilizing a stationary trailer comprises a adjustable length leg member, which may comprise the jack stands or landing gear which come as originally installed equipment on the trailer. Alternatively, the adjustable length leg members may comprise various types of jacks which are later attached to the bottom of the trailer. The apparatus further comprises a ground engaging base plate which is attached to the end of the adjustable length leg member. The ground engaging base plate comprises attachment means for one or more stabilizer members. The first end of the stabilizing member attaches to the ground engaging base plate and the second end of the stabilizing member attaches to an attachment member depending from the bottom of the trailer. The attachment member is adapted to slidably receive the second end of the stabilizing member. The attachment member comprises locking means for engaging the stabilizing member and locking the stabilizing member with respect to the attachment member. The locking means allows the length of the stabilizing member disposed between the ground engaging base plate and the attachment member to be adjusted and locked as desired to increase the stability of the trailer.