Source‐based writing assignments conducted by groups of students are a common learning task used in information literacy instruction. The fundamental assumption in group assignments is that students' collaboration substantially enhances their learning. The present study focused on the group work strategies adopted by upper secondary school students in source‐based writing assignments. Seventeen groups authored Wikipedia or Wikipedia‐style articles and were interviewed during and after the assignment. Group work strategies were analyzed in 6 activities: planning, searching, assessing sources, reading, writing, and editing. The students used 2 cooperative strategies: delegation and division of work, and 2 collaborative strategies: pair and group collaboration. Division of work into independently conducted parts was the most popular group work strategy. Also group collaboration, where students worked together to complete an activity, was commonly applied. Division of work was justified by efficiency in completing the project and by ease of control in the fair division of contributions. The motivation behind collaboration was related to quality issues and shared responsibility. We suggest that the present designs of learning tasks lead students to avoid collaboration, increasing the risk of low learning outcomes in information literacy instruction.