Along with independent writing tasks, integrated writing tasks in which learners use
oral/written input sources to develop their writing has received rising attention during the recent
decades. These two writing types have been in use in both classroom and high-stakes assessments.
Hence, improving the writing practice gets significant. Among different variables that affect the
writing of the students, the role topical knowledge plays in writing performance of the students in
the two independent and integrated writing has not been investigated. Therefore, this study was
conducted to examine the effect of topical knowledge on the writing performance of the students
in two independent and integrated modes. To achieve this goal, a body of 44 EFL male and female
students at Persian Gulf University were randomly assigned into one independent and one
integrated group. The students in both groups were given the same topic to write. While
independent group received no accompanying text, integrated group learners were given a reading
passage relevant to the topic. The results of independent samples T-test showed that topical
knowledge had a significant effect on integrated writing performance of the students compared
with independent writing. The findings of this study imply that the teachers can use integrated
writing with a strong foundation of knowledge related to the topic to further enhance writing
performance of the students.