Much attention has been paid to the complexity underlying writing, but the versatile roles that collaborative writing can encourage in elementary students remain scarcely understood. In this exploratory study, we developed a framework for observing the participatory roles that elementary students spontaneously adopt as they engage in collaborative writing in environmental and social studies classrooms. To concretize the applicability of the framework, we illustrate how five students shift between the roles across task types. We identified 18 participatory roles and allocated them into six categories: content-, literacy-, performance-, process-focused, expressive, and off-task roles. While these generally align with previous research on participatory roles, literacy-focused and expressive role categories emerged as new data-driven findings. The concrete examples provided for illustrating how these roles are reflected when students engage in collaborative writing deepen the understanding of the variety and flexibility in roles adopted across the students and task types. We expect the framework to be beneficial for both teachers and researchers, to observe how flexibly students adopt roles from different categories when writing collaboratively. This can provide insights into designing instruction and selecting task types to effectively promote flexible and meaningful participation among all students when writing collaboratively in subject-area classrooms.