A discussion of dictionaries and their use for second language (L2) learning suggests that lack of computerized modern language corpora can adversely affect bilingual dictionaries, commonly used by L2 learners, and shows how use of such corpora has benefitted two contemporary monolingual L2 learner dictionaries (1995 editions of the Longman Dictionary of Contemporary English and Collins Cobuild English Dictionary). The 1994 edition of the Kenkyusha New College English-Japanese Dictionary and the 1995 edition of the Kenkyusha New College Japanese-English Dictionary are examined for some recent improvements and remaining linguistic deficiencies, particularly usage errors and lack of updated word frequency, collocation, grammatical, and formality information. Examination of the two monolingual dictionaries in question shows how use of natural frequency information from modern, computerized corpora influenced the selection of lexical items, definitions, examples, grammatical patterns, and pragmatics in the dictionary entries. The importance of training in dictionary use is also highlighted. Contains 18 references. (MSE)