This study used a Multi-Dimensional analysis to describe linguistic variation in thesis abstracts based on two factors: academic level and L1 background. To do so, a corpus of 1800 thesis abstracts written by MA and PhD students from three L1 backgrounds (Chinese, Persian, and English) was compiled. Our analysis revealed four dimensions of variation, interpreted as (1) extended procedural/reported discourse versus descriptive, informational discourse; (2) extended contextualization; (3) expression of argument/persuasion; (4) human-focused informational density. The results showed that Dimensions 1 and 3 distinguished between the writing practices of MA and PhD students. Additionally, Dimensions 1, 2, and 3 differentiated the writing of students across L1 backgrounds. Interestingly, the differences between L1 English and L1 Persian abstracts did not turn out to be significant, suggesting that L1 Persian students showed a closer alignment with L1 English students compared to L1 Chinese students. Finally, the interaction between academic level and L1 background was statistically significant concerning Dimensions 1 and 2, suggesting there are different trajectories between MA and PhD level students depending on the language background.

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