Introduction: Information literacy instruction is often undertaken in schools as collaborative source-based writing assignments. his paper presents the findings of a study on collaboration in two school assignments designed for information literacy. Method: The study draws on the models of cooperative and collaborative learning and the task-based approach to study information seeking and use. Data were collected by interviewing seventeen groups of upper secondary school students during and after their group projects. Analysis: Thematic analysis revealed how students cooperated and collaborated, and built a basis for joint meaning making from sources and knowledge building in their own texts. Results: Few student groups worked closely together (collaborated) in all activities: planning the work, searching, assessing and reading sources, and writing the article. Some other groups started similarly but drifted to loosely coordinated cooperation at the stage of reading and writing. About a half of the groups divided the work into independent, personal text writing tasks but failed to merge texts into a coherent article. Conclusions: The case suggests that in the present school culture group assignments may turn into loosely connected individual efforts and waste much of the group work potential both in learning about the topic area and information literacy. [This paper was published as part of: Proceedings of the Eighth International Conference on Conceptions of Library and Information Science, Copenhagen, Denmark, 19-22 August, 2013.]