In this study, a micro-level approach was used to investigate how college students in an academic writing course interact with peer and instructor feedback at "different stages" of the writing process. Participants were 146 first-year students at a Singaporean university. A survey and focus group interviews concerning students' feedback-adopting strategies were conducted. Results show that, for these students, revision was a reiterative self-regulated process sustained by the different functions of both types of feedback, which were found to serve different roles at different stages. Overall, peer feedback identifies initial issues with clarity and prompts divergent thinking while, at a later stage, instructor feedback challenges ideas and encourages evaluative thinking. It is concluded that the two feedback types are complementary and should be reconceptualized to be equally valuable and indispensable. The value of feedback should be seen as a "sequential" structure, where both sources of feedback play essential roles at different stages, rather than a "hierarchical" structure, in which instructor feedback is overwhelmingly prioritized.