The goal of this study was to explore the effect of language on English number transcoding by comparing the errors made by First Language Learners (FLL) with those made by Second Language Learners (SLL). Errors were analyzed through the lens of ADAPT cognitive model of transcoding. Eighty-seven students in grade 3 (i.e., 51 FLL and 36 SLL) were recruited from Ottawa schools. They attempted to write down 30 verbally-presented numbers which varied from 3 to 7-digits. Overall, the two groups showed similar transcoding performance. The errors increased with the number of digits and did not differ across groups. However, FLL made more syntactic errors whereas SLL made more lexical and combination errors. Although both groups made errors applying the transcoding procedures, some SLL were still developing their numerical lexicon. Individual differences in transcoding were related to visual-spatial and verbal working memory. The results align with ADAPT model of number transcoding.