This essay explores how students' misconceptions about writing might be transformed into accurate threshold concepts of writing through disciplinary writing experiences. Through an activity analysis of a geology major and students' writing in that program, I demonstrate that these students' conceptions of writing changed through their legitimate peripheral participation in geological activity. Students' learning in the major situated writing within the activity of professional geological communities, and they recognized both how writing constructs and circulates knowledge within their discipline and their need for writing to enable participation in those communities. Their example suggests that WID programs attend to conceptual change and legitimate peripheral participation as essential mechanisms for creating transformative writing experiences that enable student learning.

This double issue of Across the Disciplines features seven articles, as well as a book review. I am confident that individuals interested in research on WAC faculty development, writing in STEM, threshold concepts of writing, and writing transfer will find much of value. Two articles take up the central WAC matter of faculty development: Elisabeth Miller et al. ( Three contributions engage

Research on written communication shows that rhetorical knowledge is a key domain of disciplinary writing expertise (Gere et. al. 2019). Much of the recent work in this area has focused on the social dimensions of learning this knowledge. This article builds on these conversations with a presentation of two “advanced academic writers” (Tardy, 2009) and interpreting how they conceptualize rhetorical knowledge through an understanding of academic communication as transaction and symbolic exchange (Britton & Pradl, 1982). I make a case for the value of a transactional framework for interpreting writers’ performance of genre situations. I also show that this framework can provide a “metagenre” (Carter, 2007), a way of doing writing in the discipline, and a “threshold concept” (Adler-Kassner & Wardle, 2015), a way of thinking about writing tasks that shapes writers’ experiences of and learning with them. The two case studies provide an argument for the efficacy of rhetorical knowledge in fostering disciplinary genres when it is framed as understanding situations of communication.