This paper reports two studies into the efficacy of sentence openers to foster online peer-to-peer interaction. Sentence openers are pre-defined ways to start an utterance that are implemented in communication facilities as menu’s or buttons. In the first study, typical opening phrases were derived from naturally occurring online dialogues. The resulting set of sentence openers was implemented in a semi-structured chat tool that allowed students to compose messages in a freetext area or via sentence openers. In the second study, this tool was used to explore the students’ appreciation and unprompted use of sentence openers. Results indicate that students hardly used sentence openers and were skeptical of their usefulness. Because both measures were negatively correlated with students’ prior chat experience, optional use of sentence openers may not be the best way to support students’ online interaction. Based on these findings, alternative ways of using sentence openers are discussed and topics for further research are advanced.