Bowker (1998) has pointed out that the use of specialized native-language corpora was influential in improving the quality of a translation in terms of “correct term choice, and idiomatic expression” (1998, 648). The author here argues that Bowker’s findings can be extended to the general language as well if we understand “correct term choice” as collocation and “idiomatic expression” as native-like production. Both these aspects are part and parcel of what is known as “conventionality in language”, lack of knowledge of which characterizes an “innocent speaker” (Fillmore, 1979), a concept that can equally well be applied to the translator. The translator’s innocence can transpire both in his comprehension and production abilities. Despite a few conventional reference sources he has at his service (some mono- and bilingual dictionaries of idiomatic expressions, a few dictionaries of formulas and collocations, mostly monolingual), they do not provide natural native-like options at all times. This is where a corpus can fill the gap. This paper discusses the compilation and use of a bilingual corpus by students of a Diploma Course in Translation at the University of São Paulo, Brazil.