Are regular morphologically complex words stored in the mental lexicon? Answers to this question have ranged from full listing to parsing for every regular complex word. We investigated the roles of storage and parsing in the visual domain for the productive Dutch plural suffix -en.Two experiments are reported that show that storage occurs for high-frequency noun plurals. A mathematical formalization of a parallel dual-route race model is presented that accounts for the patterns in the observed reaction time data with essentially one free parameter, the speed of the parsing route. Parsing for noun plurals appears to be a time-costly process, which we attribute to the ambiguity of -en,a suffix that is predominantly used as a verbal ending. A third experiment contrasted nouns and verbs. This experiment revealed no effect of surface frequency for verbs, but again a solid effect for nouns. Together, our results suggest that many noun plurals are stored in order to avoid the time-costly resolution of the subcategorization conflict that arises when the -ensuffix is attached to nouns.