This article investigates modal auxiliaries in original and translated Afrikaans and South African English parliamentary discourse in the period 1925–1985. Against the background of the sociolinguistic history of language contact in the bilingual South African parliament (1910–1994), it analyses (a) the contrastive differences in the use of modal auxiliaries in South African English and Afrikaans, (b) potential cross-linguistic influence in the use of modals between the two languages, and (c) the way in which contrastive differences and cross-linguistic influence are reflected in translations. In both languages, modal auxiliaries are more common in parliamentary discourse than in general usage. There is little evidence of overall convergence; there are, however, cross-linguistic similarities in specific pragmatic uses of modals in parliament. Translations show a large degree of shining-through from the source text, alongside adjustment to target norms; the tension between these two forces is variable, and influenced by social factors.