This study aimed to investigate the realization of marked and unmarked theme types as point of departure of message in general English texts. The corpus of this study was 15 general English texts extracted from English general textbooks for university students published in Iran and taught at universities in Iran. The corpus was analyzed based on Halliday’s (1985) framework of thematic organization. Findings suggested the unmarked theme was predominant compared to marked theme. This is due to that writers prefer to use simple structure that help readers to get a better comprehension. Findings also showed that different types of marked theme were used to help in text organization and contribute to better comprehension. In such cases, the writers felt the need to mention some elements in the thematic position other than grammatical subject. The findings highlighted that general English instructors and developers need to take on board the notion of theme and its importance in teaching and developing general English texts.