Background/purpose: Academic writing in English as a Foreign Language (EFL) poses challenges for graduate students, particularly in achieving coherence and organization. Thematic choices play a crucial role in guiding readers and ensuring textual cohesion. While Theme selection has been explored in various contexts, little research has examined how Saudi female graduate students use thematic structures across academic genres. This study investigates their thematic choices to understand how they adapt to academic writing conventions and genre expectations. Materials/methods: The study analyzed 108 written assignments from Saudi female graduate students across different academic genres. Semi-structured interviews with 18 students provided further insights into their thematic choices and writing strategies. Using a content analysis approach based on Systemic Functional Linguistics (SFL) theory, particularly Martin and Rose's (2007) semantic approach, the study categorized thematic structures into topical, textual, and interpersonal Themes to assess their distribution and function. Results: Findings reveal a dominant use of topical, unmarked Themes across all genres, with variations in marked, textual, and interpersonal themes. Research papers featured more topical, unmarked Themes, reinforcing subject focus and formality, while essays used more textual and interpersonal Themes for engagement and flow. Genre expectations influenced students' thematic choices, reflecting their awareness of academic writing norms. Conclusion: This study underscores the importance of Theme selection in enhancing coherence and aligning with genre conventions. The findings contribute to SFL research by highlighting how Theme variation supports textual cohesion and communication goals, offering insights for improving EFL academic writing instruction.