This paper presents the creation of the Qatari Corpus of Argumentative Writing (QCAW) as an annotated L1 Arabic and L2 English bilingual writer corpus. It comprises 200,000 tokens of argumentative writing by Qatari university students in L1 Arabic and L2 English. The corpus includes 195 essays written by 195 students, 159 females and 36 males. The students were native Arabic speakers proficient in English as a second language. The corpus is divided into Arabic and English sections, accompanied by part-of-speech annotated files. The Metadata contains information about the students (gender, major, first and second languages) and the essays (text serial numbers, word limits, genre, writing date, time spent, and location). The paper outlines the steps for collecting and analysing the corpus, including details on essay writers, topic selection, pre-analysis text modifications, proficiency level, gender, and major ratings. Statistical analyses were applied to examine the corpus. The QCAW offers a valuable bilingual data source authored by the same students in Arabic and English, with implications for further research