Tests have been performed to compare the double- and single-shear strengths of joints in DTD 546b light alloy sheets using Avdel blind rivets. The tests were an extension of work done on solid rivets, and followed conventional procedures. The double-shear proof and ultimate strengths were found to be appreciably better than the single-shear strengths over a useful range of sheet thickness/rivet diameter ratio. The effect of manufacturing tolerance was examined and found to be important, though adherence to the rivet manufacturer’s recommended procedures ensures good strength. The above conclusions lead to a consideration of the physical behaviour of the joints which is seen to differ in three ranges of thickness/diameter ratio.