It has sometimes been claimed that dictionaries which reflect the mental lexicon as faithfully as possible are likely to be more functional than dictionaries which do not. In this contribution, some fundamental properties of dictionaries which tend to create problems in this connexion are discussed. In particular, the way entry forms are traditionally selected in dictionaries and the lemmatization concept in itself give rise to asymmetries alien to the information network of the mental lexicon. However, Iexicographers can contribute considerably when a realistic mode! of the lexicon is being established.