Using a speeded-naming variant of the picture-word task, we found that word substitution errors can be elicited in the laboratory. In this variant of the task, participants often responded by saying the word instead of the picture's name. Such word substitution errors are interesting because they allow the evaluation of the relative merits of two broad classes of word production models. We obtained evidence in support of interactive models of word production. In addition, the error data presented evidence that speeded naming taps a late, name retrieval process and that picture naming is semantically mediated.