Uncle Tom’s Cabin, Harriett Beecher Stowe’s influential anti-slavery novel, appeared in eight different Welsh-language versions (translations, abridgements and adaptations) between 1852 and 1854. This paper looks at the representations of spoken language in these translations, especially the language of the uneducated slaves and other characters represented by Stowe as speaking varieties other than standard English. The Welsh translators, to varying degrees, seem to have been sensitive to the register variation as represented in the original. They equated standard spoken English with written literary Welsh, and Southern White Vernacular English (SWVE) with the translator’s own spoken regional dialect. In addition, in their translation of early African-American Vernacular English (AAVE), they included various other features, auxiliary deletion and postnominal pronouns in possessor constructions, which are known in nineteenth-century Welsh literature only from representations of second-language, non-native Welsh. These structures have, however, become part of the informal colloquial spoken Welsh of first-language speakers today, supporting existing approaches that view their innovation and diffusion as being due to language contact with English.