Situating journalism as a cultural practice charged with delivering valid accounts of the world necessitates a theory of metajournalistic discourse to explain how meanings around journalism develop. Through metajournalistic discourse, various actors inside and outside of journalism compete to construct, reiterate, and even challenge the boundaries of acceptable journalistic practices and the limits of what can or cannot be done. Based on the premises that journalism is variable, reliant on context, and produced through social relationships, this article develops a theory of metajournalistic discourse that connects three components—actors, sites/audiences, and topics—to processes of definition making, boundary work, and legitimation.