This study explored noun and verb retrieval using a sentence completion task to expand upon previous findings from picture naming tasks. Participants completed sentences missing either a target noun or verb in the final position. Non-target responses were coded for substitution type, imageability and frequency. Like picture naming, nouns and verbs differed in non-target substitution type--within-category substitutions were primarily nouns and out-of-category substitutions were primarily verbs. Imageability predicted multiple substitution types for both word classes, whereas frequency predicted noun substitution types but not verbs. Findings support theories of noun and verb differences in semantic retrieval, showing the robustness of this effect across methodologies, and shed new light on the influence of imageability and frequency during semantic retrieval.