Communication for informed choice is particularly challenging in clinical settings such as direct-entry midwifery, where the care model embraces diverse therapies and forms of knowledge. We identified three discursive moves (explanation, invocation, and evaluation) that Ontario midwives and clients used in making claims about proposed interventions. The analysis was informed by an understanding of communication as an interactionally situated and socially constructed interpretive practice. Both midwives and women called on the authority of biomedical discourse, but they also turned to sources such as women's wisdom to support their cases. The flexible use of these moves afforded participants considerable latitude in accepting or rejecting forms of evidence as authoritative. However, strategies designed to empower clients in making choices could unintentionally serve to enhance the authority of the care provider. Talk about interventions brings into view both the knowledge systems and the broader relations within which regulated midwifery practice operates.