Abstract
Background. Lexical Bundles (LBs) have become the focus of many recent corpus linguistics studies. Research has found variable use of LBs in terms of quality and quantity pertaining to different linguistic groups or registers. Still, there is a paucity of research investigating Arab EFL writers' use and development of such a feature.Purpose. This study investigates the 4-word LBs use and development by Arab EFL learners and expert writers in a corpus of 250000 words regarding their frequency, functions, and structure. Methods. Two corpora were compiled for Arab learners and scholars. The LB use of both groups was compared to investigate the development of LB use. Further, the Arab corpus was analysed against a native reference corpus extracted from the British Academic Written English (BAWE) corpus to compare LB use across the two corpora.Results and Implications. The results imply that there is no noticeable effect of postgraduate education or professional practice on using LBs. The other results, however, are in-line with the previous literature in that native speakers' use of LBs varies in quantity and quality from non -natives'. The findings reveal that stance LBs are more frequent in the native corpus and that they tend to use more VP-based clausal LBs than their non-native counterparts. These findings offer empirical evidence that EFL writing quality is lower despite the current academic writing instruction they receive. They, therefore, indicate the need to foster academic writing instruction programs to include training on using LBs in learners' writing at both Bachelor and postgraduate levels. Also, the results are expected to raise teachers' awareness of how EFL learners use LBs to develop their writing quality and thus to adapt their teaching strategies accordingly. Moreover, Arab scholars are called to reconsider their use of effective writing techniques including LBs for more effective writing.