In the research reported here, we investigated the influence of phonological neighborhood density on the processing of words in the visual lexical decision task. The results of the first experiment revealed that words with large phonological neighborhoods were verified more rapidly than words with small phonological neighborhoods. In the second experiment, we replicated this effect with a more tightly controlled set of stimuli. These results demonstrate the importance of phonological codes when processing visually presented letter strings. We relate this research to previous results on semantic and orthographic neighborhoods and discuss the results within the context of a model in which lexical decisions are based on stimulus familiarity.