Policy makers today rely primarily on technical data as their basis for decision making. Yet, there is a potentially underestimated value in substantive reflections of the members of the public who will be affected by a particular regulation. Viewing professional policy makers and professional commenters as a community of practice, we describe their limited shared repertoire with the lay members of the public as a significant barrier to participation. Based on our work with Regulation Room, we offer an initial typology of narratives--complexity, contributory context, unintended consequences, and reframing--as a first step towards overcoming conceptual barriers to effective civic engagement in policy making.