© Lexicography in Global Contexts. The paper deals with the principles of constructing the first printed and on-line English-Russian dictionary of idioms based on corpus data. The need for a new dictionary of idioms is motivated by the fact that there is presently no corpus-based dictionary of English-Russian idioms built on authentic examples. Existing traditional bilingual dictionaries do not meet modern requirements of the present-day lexicography with respect to vocabulary and illustrative examples, which are often out of date. This is definitely connected with the fact that traditional English-Russian idiomatic dictionaries were constructed in the 'pre-corpus era'. The purpose of the present research is thus to introduce a methodology for generating a comprehensive idiom list of the dictionary, to consider linguistic issues presenting difficulties in bilingual lexicography related to the concept of equivalence in idioms, and analyze the semantic asymmetry between English and Russian idioms.