Experimental evidence suggests that pictorial elucidation helps learners comprehend and remember the meaning of second language (L2) idioms. In this article we address the question whether it also helps retention of the form of idioms, i.e. their precise lexical composition. In a small-scale experiment, the meaning of English idioms was clarified to students with reference to the original, literal use of the expressions. This was done with a view to stimulating dual coding, i.e. the association of the figurative phrases with images of concrete scenes. For half of the idioms, photographs or drawings depicting those concrete scenes were added to the verbal explanations. The learners' recollection of the content words of the expressions was subsequently gauged in a gap-fill test. Overall, the results suggest that the addition of pictorial elucidation contributes little to learners' retention of linguistic form. Distraction by pictures may even have a detrimental effect when it comes to retaining unfamiliar and difficult words, and this seems to apply especially to learners whose learning style shows a predisposition for processing vocabulary through imagery. Insofar as our findings are transferable to vocabulary learning in general, they may call into question the rather indiscriminate and abundant use of pictorials in modern textbooks and CALL packages.