One joining technique that is receiving increased attention is mechanical fastening with a steel self-piercing rivet. The use of steel rivets in direct contact with aluminum components raises questions concerning galvanic corrosion. To determine if a corrosion problem exists, aluminum samples were joined by two processes--resistance spot welding and steel self-piercing rivets.Replicate samples using two aluminum alloys were tested for 90 days by alternate immersion in 3.5% NaCl water solution. After alternate immersion exposure, the integrity of the joint was evaluated by shear testing. Joint shear strengths and the metallographic corrosion evaluations are presented in this paper.