This paper explores the activity of collaborative playwriting for theatre performance as a mode of language learning within a task-based framework. It describes a quasi-experimental study in which a pair of similar but distinct playwriting theatre tasks was implemented in a first-year English oral communication course at a senior high school in Japan. This paper briefly discusses the background, rationale and design of the playwriting tasks. It then reviews relevant data obtained from post-task student feedback questionnaires. Despite the evident lack of theatrical experience amongst the student participants, their feedback was markedly positive. In addition, a number of students reported improvements in various areas of their language abilities. They also recognised the opportunities for learning that both the devising process and the performance outcomes afforded them.