The development of written accuracy among learners of English as a Second Language (ESL) has always been a primary concern for ESL teachers and researchers in Applied Linguistics and Second Language Acquisition (SLA). While a vast body of research has examined learners‘ interlanguage, proposed taxonomies of errors made by ESL learners, and explored their possible sources (such as intra-lingual and inter-lingual transfer, cross-linguistic interference and first language (L1) interference), few studies have focused on the development of written accuracy among Arabic speaking learners of English. Yet, given the differences between Arabic and English, the potential for interference errors is high. Furthermore, traditional teaching approaches in the Arab world, which are primarily product-oriented, have been said to negatively impact on students‘ perceptions of and attitudes towards ESL writing, and consequently on their language development. This case-study examines firstly the level of written accuracy of Bahraini learners of English in their first year at a higher education institute, highlighting not unexpectedly, a high frequency of L1 interference errors. The investigation then explores the impact that a process-oriented instructional approach had on learners‘ writing in English as a foreign language, tracking development over the course of an academic semester. The intervention applied to improve learners‘ skill development involved a significant peer-reviewing component in addition to individual and collective teacher feedback. A corpus of students‘ initial writings and subsequent revisions, as well as peer-reviews, was analysed to identify whether there was an improvement in the accuracy of students‘ texts. It was found that a process-oriented approach and peer-reviewing appeared to assist students‘ learning, as they were able to identify L1 interference errors in the work of their peers. However, there were variable results in students‘ abilities to apply this learning to different writing contexts. This suggests that more time is needed to practise and embed the skills learned, especially for Arabic speaking students learning to write in English, due to the highly different language structure of their first language compared to L2. The results provide new insights into the dynamic relationship between producing correct forms and noticing errors in one‘s peer‘s writing with several pedagogical implications for teaching writing to Arabic speaking students in the Bahraini context including the need to establish an approach to understanding the written skills of learners require and to provide them with the proper training and scaffolding addressing their language needs.