Research to-date has not successfully demonstrated consistent neural distinctions for different types of ambiguity or explored the effect of grammatical class on semantic selection. We conducted a relatedness judgment task using event-related functional magnetic resonance imaging (fMRI) to further explore these topics. Participants judged relatedness within word pairs. Consistent and inconsistent conditions were included along with filler items. Imaging results revealed a main effect of ambiguity in the dorsolateral prefrontal cortex (DLPFC) and parietal cortices. A main effect of grammatical class was observed in the parahippocampal and lingual gyri, and a main effect of consistency was found in the DLPFC, ventrolateral prefrontal cortex (VLPFC) and occipital cortices. Interactions among these factors were observed in the cingulate gyrus and motor cortices in addition to the DLPFC. These results suggest that both ambiguity type and grammatical class modulate semantic selection through different neural regions. (Contains 3 tables and 3 figures.)