This dissertation explores the relationship of plain language—a popular strategy for creating effective, ethical, and cost-effective texts—and audience. Specifically, it examines the impacts of plain language revision on insider and expert audiences in the case of a city charter plain-language revision. Through qualitative analysis and a genre theory approach, I found that the plain language charter affected insiders through various sites of interplay, or residual connections between the old and new charters. Insiders and experts contended with an interplay of charter authorities, as well as an interplay of practices, which included easier individual reading and improved government processes. In addition, through an interplay between genres, the plain language charter affected the form of other texts in the government. This project has implications for technical and professional communication research and practice. It also has implications for rhetorical theory, as the project inquires into what plainness currently is and does for writers and audiences. I explore plainness as a durable rhetorical style type that is currently bound up with an ideology favoring public access and participation in expert spheres. I also take up Devitt’s (2009) call to refigure form and style into studies of genre—a framework that I show is enriching for context-focused research into plain language.