Scientists play an important role in framing public engagement with science. Their language can facilitate or impede particular interactions taking place with particular citizens: scientists’ "speech acts" can "perform" different types of "scientific citizenship". This paper examines how scientists in Australia talked about therapeutic cloning during interviews and during the 2006 parliamentary debates on stem cell research. Some avoided complex labels, thereby facilitating public examination of this field. Others drew on language that only opens a space for publics to become educated, not to participate in a more meaningful way. Importantly, public utterances made by scientists here contrast with common international utterances: they did not focus on the therapeutic but the research promises of therapeutic cloning. Social scientists need to pay attention to the performative aspects of language in order to promote genuine citizen involvement in techno-science. Speech Act Theory is a useful analytical tool for this.