Unlike the joining of metal structures, the requirements for geometric sizing of a composite, mechanically fastened joint are often more critical, particularly when the joint is bearing primary loads. This concern stems from the relative weak shear and bearing strengths of composite laminates. For adhesively bonded joint design, the free ends of the joint are the critical locations where particular care must be taken to ensure peeling stresses are kept low and the traction-surface has the correct ply orientation. This chapter provides a detailed understanding of the unique requirements for the mechanical fastening of composite structures and how to design adhesively bonded joints to allow full load transfer, which will be related to the repair of composite structures.