In many elections - especially those using single-member constituency systems - the allocation of seats is incommensurate with each party's share of the votes cast. Seats, Votes and the Spatial Organisation of Elections provides a convincing, rigorous analysis of this disproportionality which has not been improved on since its publication over 30 years ago. Its formal analysis, illustrated by empirical examples from a range of countries, stresses the importance of three geographies as key influences on how votes are translated into seats: the geography of partisan support (where people with different political persuasions cluster); the homogeneity of those clusters; and their relative size. Its re-publication makes this classic piece of spatial (political) science available to contemporary audiences, for whom it is as relevant as when the book first appeared in 1979; Ron Johnston's introductory essay sets the work in context and identifies its importance as the foundation for three decades of subsequent work into this key feature of electoral system operation.