Attach as many cabinets together as you can safely lift and install on the ledger board -- usually two. Use clamps to fix the stiles (the vertical pieces on the face of the cabinet frames) of the cabinets together and check for plumb, making sure the fronts of the cabinets are flush.
Next, predrill and secure the two cabinets together at the stile with the screws (Image 1). Affix one screw on the top and bottom in the front and back where the two cabinets meet.
Lift the cabinets onto the ledger board and check for plumb and level. Shim the cabinets if necessary.
Once you have shimmed for plumb and level, secure the cabinets into the wall at the studs. Be sure to predrill and affix the screws through the thicker framing piece along the top of the cabinets.
Check for plumb and level while you’re securing the cabinets. Repeat this process for all of the wall cabinets. If a gap exists between wall and the last cabinet, use a filler bar (supplied by the manufacturer) to enclose the gap. Before securing the last cabinet, measure, mark, cut and secure this piece to the side of the last cabinet.
After all the cabinets are in place, attach the doors and hardware. Remove the ledger board when you are finished installing the wall cabinets.