English as an additional language (EAL) and language diversity attract much interest amongst policymakers and educationists; yet little is known about the performance in English schools of EAL pupils who are not fluent in English and speak different languages at home. The findings of the aggregated data confirm that EAL pupils achieved less well at Reading, Writing and Maths at Key Stage 2 (KS2) than those with English as their first language. It also suggests smaller achievement gap in England and a wide variation in performance between regions. However, it is important to note that using EAL status alone is not necessarily an accurate marker for studying EAL attainment. The EAL variable in the National Pupil Database is blunt and includes EAL pupils who are fully fluent in English and pupils who recently arrived as migrants who speak little or no English. We would argue that EAL is a very heterogeneous group made up of pupils from many different linguistic and ethnic backgrounds and different stages of proficiency in English, which are likely to show a wide variation in achievement. Further analysis of the data by language spoken at home and level of fluency in English highlighted the potential to disaggregate EAL categories and attain a greater insight into their performance. The study confirms that EAL pupils not fluent in English are underachieving compared to monolingual English speakers in English schools.