Although pair and group work are commonly used in language classrooms, very few studies have investigated the nature of such collaboration when students produce a jointly written text. This study set out to investigate collaborative writing. The study was classroom based, and the participants (23) were adult ESL students completing degree courses. Students were given a choice to write in pairs or individually. Although most chose to work in pairs, some chose to work individually. All pair work was audiotaped and all completed texts collected. All pairs were also interviewed after class. The study compared texts produced by pairs with those produced by individual learners and investigated the nature of the writing processes evident in the pair talk. The study also elicited the learners' reflections on the experience of collaborative writing. The study found that pairs produced shorter but better texts in terms of task fulfilment, grammatical accuracy, and complexity. Collaboration afforded students the opportunity to pool ideas and provide each other with feedback. Most students were positive about the experience, although some did express some reservations about collaborative writing.