L2 writing was once considered a solitary endeavour, but contemporary studies increasingly cover collaborative writing (CW), as noted by Lázaro-Ibarrola (2023). Yet, few EFL studies address CW in primary education, and even fewer include learner perspectives on CW (but see, e.g., Azkarai & Kopinska, 2020), which aid the understanding of pupils’ actions and language learning outcomes (Storch, 2013). The present study seeks to redress this lack by focusing on young learners’ perceptions of CW and their CW process. It reports on an intervention in Swedish school year 5, where 51 EFL learners (age 11) collaboratively wrote narrative texts. The digital CW process of ten pairs of pupils was documented using audio- and screen recordings that illuminate how challenges were resolved and provide a basis for exploring learner relationships. These pairs also shared perceived benefits and challenges of CW in pre- and post-intervention interviews. An inductive thematic analysis of the interviews was conducted, whereas the recordings were analysed deductively drawing on Storch’s (e.g., 2013) model of dyadic interaction. Preliminary results suggest that pupils identify linguistic benefits, such as vocabulary learning, and believe CW to facilitate the generation of new ideas. Challenges described concern writers having different opinions or distracting each other. The audio- and screen recordings tentatively indicate spelling as a problem, usually resolved using Google Translate, while the learner relationships are pending further analysis. Once analysed in its entirety, the data underlying the present study promises new insights into the potential of CW in primary school.