A method of installing a support structure is provided for use in soft or unstable soil. The method forms a hole in the earth to a depth sufficient to support the structure, such as a utility pole or post. A pole support is placed in the hole and driven downward into the earth to form a supporting base at the bottom of the hole. The pole support in one embodiment has a helical screw at a bottom end and a flat supporting plate at the top end. The pole support is rotated by a drive member into the earth to position the support plate at the bottom of the hole. The support plate can have a hole in the top face to receive the drive member for rotating the support member to drive the screw into the earth. The drive member is then separated and lifted from the hole. The pole or post is positioned on the support plate and the hole is back-filled.