The spelling of many disyllabic English word endings holds cues to their grammatical category, beyond obvious inflectional endings such as "-ing" for verbs. For example, some letter sequences are clearly associated with nouns (e.g., "-oon") and others with verbs (e.g., "-erge"). This study extended recent research by Arciuli and Cupples (2006), and confirmed that skilled adult readers are sensitive to these orthographic cues. It was found that adults were more likely to treat pseudowords as nouns when they had noun-like endings than verb-like or control endings, and more likely to treat pseudowords as verbs when they had verb-like than noun-like endings. This sensitivity held across three tasks (sentence construction, sentence judgement, and pseudoword judgement), which required increasingly explicit awareness of the way that cues could allow grammatical categorisation. In some tasks sensitivity to verb-like endings was related to reading ability, although not to spelling ability or grammatical awareness. Implications for our understanding of language processing are discussed.