Many governments offer significant inducements to attract inward investment, motivated by the expectation of spillover benefits. This paper begins by reviewing possible sources of spillovers. It then provides a comprehensive evaluation of the empirical evidence on productivity, wages and exports spillovers in developing, developed and transitional economies. Although theory can identify a range of possible spillover channels, robust empirical support for positive spillovers is hard to find. The reasons for this are explored and the paper concludes with a review of policy aspects.