Collaborative inquiry groups, such as professional learning communities and lesson study groups, are proliferating in schools across the United States. In whatever form, the potential for impacting student learning through this collaborative work is expanded or limited by the nature of teachers' conversations. Polite, congenial conversations remain superficially focused on sharing stories of practice, whereas collegial dialogue probes more deeply into teaching and learning. Examples of talk taken from collaborative teacher inquiry groups are used to illustrate these important differences. Specific recommendations are provided, including the role that teacher leaders can play in adopting and modeling specific strategies that support the use of more substantive professional conversation.