The application describes a bilateral drilling and screw placement guide adapted for fixation to the spinous process of a vertebral body. The positioning and surgical guiding instrument is adapted for use during a spinal surgical procedure in conjunction with a drilling tool, fastening device, e.g. a pedicle screw, K-wire or the like. The guide includes an engagement device for attachment to a region of the spinous process, to which an adjustably attached support member is affixed. This allows for immobilizing the guide upon the spinous process anatomical landmark, in a specific orientation with respect thereto. The guide includes a bilaterally adjustable drill guide assembly for precise anatomical positioning of the drill and screw placement guides bilaterally about the sagittal, axial and coronal planes so as to enable the defining of a plurality of drilling axes extending toward the vertebral body. The device further provides for adjustment to account for anatomical variations in width along the axial plane, and includes pointing and angular positioning functionality to insure repeatable and reliable pilot hole and screw placement along a plurality of angles.