This chapter provides information not only about the kind of corpus data that are available to the researcher and translator, but also about what is not yet available. In doing so, the authors review different types of multilingual corpora and explore the different purposes to which they may be put. A strategy for building multilingual corpora is outlined that meets both the needs of researchers and the needs of eventual consumers of corpus-based research. In presenting this programme of research, they draw on experience gained in a number of multilingual corpus-building projects in Lancaster.