According to the unitization account, letters are more often missed in function words (e.g., the) than in less common content words because their higher familiarity allows access to their whole-word representations. The present study, however. replicated this pattern with nonwords. For both Hebrew and English, nonwords produced more detection errors when placed in function slots than in content slots. A similar effect was found for Hebrew prefix nonwords, where the initial letter could be interpreted as a function morpheme or as part of the stem. The results were seen as support for a structural model in which function morphemes are initially utilized to define the structural frame of a phrase but recede into the background as meaning is uncovered. Several interactive patterns illuminated the details of frame extraction.