A rivet has a head and an elongated shank of generally circular cross section extending axially therefrom. The head has a periphery including a multiplicity of spaced portions projecting radially outwardly of the periphery of the shank and at least three guide portions between these projecting portions which provide guide surfaces extending axially of the rivet with their root surface disposed in substantial axial alignment with the periphery of the shank. The head may have a configuration shaped like a dome, or an inverted frustoconical element, or a prism, and the guide portions can be arcuate in transverse section or rectilinear. The rivet shank may have a groove along its length to facilitate securing of the workpieces therewith without requiring upsetting of the shank, and the shank may have a sharp cutting edge at its free end to facilitate penetration of the workpieces to avoid the necessity for predrilling and the like. A rivet guide member is cooperatively configured to provide axially extending guide elements along a channel therethrough, and these orient the rivet guide surfaces thereagainst with the projecting portions of the rivet head extending into the spaces therebetween.