It is argued that the correct understanding and teaching of the special theory of relativity are still impaired by a number of specific, widespread misconceptions. To remove these, the relevant definitional, experimental, and philosophical foundations of the kinematics of the theory are made explicit by reference to the following issues: (i) the relativity of simultaneity, which arises, in the first instance,withinasingleGalilean frame, (ii) the principle of the constancy of the speed of light, which rests on threedistinctexperimental facts as well as on an important convention, made possible by a fourth experimental result, (iii) the compatibility of the invariance of the speed of light with theabsenceof a retardation on the part of moving clocks, and the role of that optical principle in the deduction of the Lorentz transformations, (iv) the merits of thead hoccharge against the Lorentz-Fitzgerald contraction hypothesis; the philosophical sources of the difference between Lorentz' and Einstein's interpretations of the transformation equations.