If there is such a thing as essential reading in metaphysics or in philosophy of language, this is it. Ever since the publication of its original version, Naming and Necessity has had great and increasing influence. It redirected philosophical attention to neglected questions of natural and metaphysical necessity and to the connections between these and theories of reference, in particular of naming, and of identity. From a critique of the dominant tendency to assimilate names to descriptions and more generally to treat their reference as a function of their Fregean sense, surprisingly deep and widespread consequences may be drawn. The largely discredited distinction between accidental and essential properties, both of individual things (including people) and of kinds of things, is revived. So is a consequent view of science as what seeks out the essences of natural kinds. Traditional objections to such views are dealt with by sharpening distinctions between epistemic and metaphysical necessity; in particular by the startling admission of necessary a posteriori truths. From these, in particular from identity statements using rigid designators whether of things or of kinds, further remarkable consequences are drawn for the natures of things, of people, and of kinds; strong objections follow, for example to identity versions of materialism as a theory of the mind. This seminal work, to which today's thriving essentialist metaphysics largely owes its impetus, is here published with a substantial new Preface by the author.