This paper presents a solution to the problem of synthesising multilingual speech using waveform-concatenation speech synthesis. It presents methods for mapping the pronunciations of a target-language speaker onto the sounds available in the speech corpus of a native speaker so that the resulting synthesis produces speech which can accurately represent any foreign words encountered in a predominantly native-language text by use of multi-speaker synthesis. The methods differ depending on the language-pair and on the direction of the mapping, because in the case of one-to-many phonemic mappings, highlevel features can be used, but in the many-to-one case, a physical representation of the target speech signal is required. All mappings are automatic, and the use of rule-based procedures is minimised. In this way, the methods are extensible to any language combinations. Synthesised speech samples are included with the paper so that a subjective evaluation of the results can be made.