This study explores the use of source texts in academic writing by postgraduate students from Arab backgrounds in three UK universities. The specific focus of the study is to develop an understanding of how Arab students in the UK use sources, how they adapt to UK academic expectations, as well as how their educational backgrounds may affect their source use and adaptation to UK academic expectations. The participants in this research included a group of 22 Arab postgraduate students from three UK universities. To respond to the research aims, the data generated included 40 (already assessed by their tutors) text-based assignments collected from the participants. The analysis used Pecorari and Shaw's (2012) typology as a starting point to explore the forms of intertextuality evident in the Arab students' writing. A second source of data was interviews with seven students from the same group of participants. The analysis made use of the MAXQDA data analysis software, including facilitating the textual analysis of intertextuality in the student texts and the thematic analysis of the interview transcripts. The findings suggest that unconventional use of sources does occur among this group of students, including over-reliance on sources, patchwriting, frequent use of direct quotation, and forms of paraphrasing that rely on synonym substitution. The study further suggests that unconventional use of sources may be explained by the students' past educational experiences in their Arab home contexts. This includes a lack of written culture, low readership in the region, culture of orality, acceptability of violations of copyright, and 'traditional' teaching practices in the educational systems of the region. The study also shows how the students' educational backgrounds created transition challenges for students when arriving in the academic setting in the UK. Finally, the study presents various strategies used by this group of students to adapt to the UK academic environment. The study contributes by presenting a four level framework of intertextuality, developed from the data in this study and extending on Pecorari and Shaw's typology. This includes intertextuality on the word, sentence, paragraph, and structure levels of the students' academic writing. This expanded view of intertextuality, including a level-based framework, enhances understanding of the forms of intertextuality prevalent in these students' texts, and highlights the specific challenges these Arab students have faced in their transition to become academic writers in the UK context. The thesis also concludes with what are the lessons, as evident from this study, for UK Universities in supporting Arab students.