Examination of naturally occurring cases in which a person reports that a word is on the tip of his or her tongue has led several theorists to propose that an important role is played by blocking words whose intrusions hinder access to the correct targets. As yet, however, the blocking mechanism appears to have received little direct investigation experimentally. It was studied here by adapting the classic method of Brown and McNeill in which a person is presented with a definition (...) of a rare word and uses it to attempt to generate that target word. The adaptation that was made was to append a potential blocking word to the presentation of each definition. The potential blocking words were either phonologically related to the target or not, either semantically related to the target or not, and either rare or not. Only the first of these factors exerted a significant effect—more cases of tip of the tongue were experienced when the potential blocking word was phonologically related to the target than when it was not. This result suggests that the recall of a word on the basis of its meaning may proceed via an intermediate stage characterised by partial retrieval of its phonology. (shrink)