As the number of students learning in online and flipped contexts grows, an important question arises: to what extent is it necessary to have places or activities where students interact regarding course content? The present paper looked at three flipped learning environments: one with no online collaboration, one featuring an online discussion forum and one involving online collaborative note-taking. The subjects (N = 178) were all graduate students taking a flipped version of an English scientific writing class at a university in South Korea. The results show that students in the experimental conditions with online collaboration (collaborative note-taking and discussion forums) outperformed peers in the control condition (no online collaboration) on individual writing assignments. Furthermore, there was a benefit in the experimental condition with discussion forums regarding students' group writing scores compared to the control group. These results show the value of implementing online student-to-student collaboration in flipped learning contexts and that both modes of collaboration tested herein add value to students' learning.