In this paper the author first distinguishes subtitling from other text types by focussing on the interacting communicative channels present on one hand, and the physical status on the other hand. He continues by placing subtitling in a historical perspective. In a next section he defines subtitling as a written, additive, synchronous type of translation of a fleeting and poly-semiotic text and discusses the constraints, strengths and intra-textuality of subtitling. Then he introduces the problem of subtitling idioms. After considering three modes of translation (transfer, transmutation, adaptation), he discusses some strategies for idiom translation (congruence, equivalence, correspondence, reduction, paraphrase, expansion, omission, compensation), which he categorizes in adherence, literalization, deletion and idiomatization. He looks into the way idioms are actually translated, by studying a bilingual corpus, comprising 10 translations of contemporary books and films in English and the 9 corresponding originals.