Here we investigate present tense verbal -s/zero variability in a dialect of Eastern England in which -s marking can only appear in third-person singular contexts. Our objective is to explore constraints on -s/zero marking, and to consider the grammatical function of -s in such a variety. In order to investigate this, we reanalyzed verbal -s/zero marking in 63 sociolinguistic interviews found in Peter Trudgill’s (1974) corpus from Norwich. The results show not only a significant role for subject animacy (animate subjects mark -s less than inanimates) and lexical (punctual verbs mark -s less than duratives) and structural aspect (punctual and habitual events mark less -s than durative ones), but also an interaction between animacy and aspect. To account for the findings, we draw upon the notion of differential subject marking (e.g., Aissen, 2003), which considers the role of the canonicity of arguments in accounting for morphological marking.