Drawing both on conversation analysis and text linguistics, this article retraces the emergence of a new communicative practice in an online discussion forum: Based on data from an academic learning environment, we demonstrate how peers in a student study group start using the “edit button” which allows them to modify in retrospect not only their own but also other people’s posts. This communicative practice of post editing in online discussion forums develops in four stages: It starts out as simple postings of messages on a discussion board. Next, the collocutors make use of the edit button to change their own posts, and, in a dialogical manner that of their discussion partners. Finally, it comes down to a complex form of exchange between the interlocutors who innovatively use the edit button within a single post. By using the edit button in innovative ways the participants bring together sequentially related messages in a single post that are usually spread over multiple posts. We argue that the emergence of this innovative use of the strategy of “sequential compression” (sequenzielle Verdichtung), as we shall call it, may be understood as an answer both to the affordances of asynchronous communication in discussion forums and to the learning situation which is characterized by pressure of time calling for new and innovative strategies.