Studies have shown that prereaders find globally similar non-rhyming pairs (i.e., bell–ball) difficult to judge. Although this effect has been explained as a result of ill-defined lexical representations, others have suggested that it is part of an innate tendency to respond to phonological overlap. In the present study we examined this effect over time. Beginning, intermediate and advanced readers were presented with a rhyme judgment task containing rhyming, phonologically similar, and unrelated non-rhyming pairs. To examine the role of lexical representations, participants were presented with both words and pseudowords. Outcomes showed that pseudoword processing was difficult for children but not for adults. The global similarity effect was present in both children and adults. The findings imply that holistic representations cannot explain the incapacity to ignore similarity relations during rhyming. Instead, the data provide more evidence for the idea that global similarity processing is part of a more fundamental innate phonological processing capacity.