The implementation of writing-for-learning strategies within science classrooms requires changes in the way in which students engage with the subject. Specific writing tasks require students to address concepts of science and also to focus on issues of purpose, audience, topic, method of text production, and writing type. This article reports on students' perceptions of using writing as a component of their science learning. The results, collected over 4 years, have been organized to include students' perceptions of writing in science, learning, ownership, purpose, and science. These results are then discussed in terms of students' developing metacognition and epistemologies of science. The study concludes by discussing the implications arising for further research.