This ethnographic qualitative case study explores how Bislama (a Melanesian creole and Vanuatu’s national language) influences young learners’ lexical choices in their written English in a rural Vanuatu primary school. This context presents numerous challenges for both teachers and learners, particularly in regard to the debate surrounding the use of Bislama in education and falling English literacy levels. The data was collected at a government primary school in rural Vanuatu during one term in 2013, in both a grade 3 (G3) and composite grade 5/6 (G5/6) class. The data comprise: (1) classroom observations of the English language classes; (2) writing samples collected from 7 participants in G3, and 8 participants in G5/6; and (3) post-observation interviews with the school principal, the G3 and G5/6 teachers and the 15 child participants. The data was analysed through a sociocultural theoretical lens, holistically aligning theories of mediation and the zone of proximal development with scaffolding theory and Gibson’s theory of affordances (1977; 1986). I take the position that learning is a mediated process situated in social practice with language seen as a culturally constructed artefact used to mediate learning within a particular situational and cultural context. The findings indicate that the teachers used Bislama as a linguistic resource for methodological and social purposes when teaching vocabulary in order to scaffold and mediate their young learners’ understanding of new English words. While this was reflected in some of the children’s writing samples revealing Bislama’s affordances, other samples highlighted particular challenges that Bislama poses for the children. These challenges included numerous false cognates along with phonological and orthographic influences which the Ni-Vanuatu children did not perceive, resulting in errors in their writing. Nevertheless, the data also suggests that these challenges can be overcome when the similarities and differences between Bislama and English are accurately identified. This indicates that Bislama itself does not present linguistic issues, but rather how these similarities and differences are perceived and utilized by teachers and learners. Thus, it is proposed that explicit teaching of the similarities and differences between Bislama and English can improve not only vocabulary learning, but also writing in English.