In a lexical decision experiment we investigated whether the mental lexicon is accessed directly by a visual code or by phonological mediation. Subjects were asked to make lexical decisions where phonological coding was either beneficial or detrimental. It was found that subjects used phonological coding when it was helpful and abandoned this strategy when it was a hindrance. These results support the hypothesis that lexical decisions can be based on variable coding operations. The fact that subjects were faster in classifying words when they did not rely on phonological codes is consistent with the assumption of faster visual access to the mental lexicon. Taken as a whole, these results are consistent with models which assume phonological coding to take place after lexical access as well as with models postulating parallel access to the mental lexicon. They are not compatible with models postulating mandatory prelexical phonological coding.