Arts-based approaches to public engagement offer unique advantages over traditional methods of consultation. Here we describe and assess our use of theatre as a method of public engagement in the development of health policy on preimplantation genetic diagnosis, a controversial method for selecting the genetic characteristics of embryos created through in vitro fertilization. Funding from the Canadian Institutes for Health Research and Health Canada supported 16 performances of the play Orchids in Vancouver, Toronto, and Montréal and post-performance discussion in English and French (with Hubert Doucet) in 2005. A total of 741 individuals attended. The methods used to assess audience engagement and elicit policy-relevant dialogue included in-theatre observation of audience responses, moderated post-performance large audience discussion and focus groups, audience feedback forms and researcher fieldnotes. Emphasizing process and context over emerging outcomes, we reflect on the distinctive contributions of theatre in stimulating public engagement and the need to utilize multiple methods to adequately assess these contributions. We suggest continued dialogue about the possible uses of theatre in health policy development and conclude that greater clarity is needed with regard to citizens' (as well as specific stakeholders, policy makers' and sponsors') desired outcomes if there is to be a suitably nuanced and reflexive basis for assessing the effectiveness of various strategies for public engagement.