Children learning English as an additional language (EAL) are a growing population of learners in English primary schools. These children begin school with differing levels of English language proficiency and tend to underperform in relation to their non-EAL peers on measures of English oral language and reading. However, little work has examined the developmental trajectories of these skills in EAL learners in England. EAL learners and 33 non-EAL peers in Year 4 (age 8-9 years) were assessed at three time points over 18 months on measures of oral language (vocabulary, grammar and listening comprehension), phonological processing (spoonerisms and rapid automatised naming) and reading skills (single-word decoding and passage reading). At t1, EAL learners scored significantly lower than non-EAL peers in receptive and expressive vocabulary (breadth but not depth), spoonerisms and passage reading accuracy. Contrary to previous research, no significant group differences were found in listening or reading comprehension skills. With the exception of passage reading accuracy, there was no evidence for convergence or divergence between the groups in rate of progress over time. After three years of English-medium classroom instruction, EAL learners continue to underperform relative to their non-EAL peers in breadth of English vocabulary knowledge. This discrepancy in vocabulary knowledge does not appear to narrow as a result of regular classroom instruction in the run up to the final stages of primary school, pinpointing vocabulary as a key target for intervention.