This basic qualitative study explored the perceptions of industry expert adjunct faculty on writing-in-the-disciplines to support students' development of professional writing skills. Theoretical foundations for this research were formed through a social constructivist lens, with threads of co-constructions of knowledge, active participation, and motivation as elements of situated learning theory, disciplinary literacy theory, and theory of andragogy. Prior research was explored to discover the writing experiences and teaching preparation of industry expert adjunct faculty members, the influence that adjunct employment experiences have on adjunct faculty perspectives, writing instruction in higher education, and writing norms of professional disciplines. This study provides data from 11 semi-structured interviews with adjunct faculty members who teach disciplinary courses in higher education. Interviews were conducted virtually. Teaching philosophy statements also were collected through a digital drop box for document analysis from five of the participants. Three research questions guided this study to discover the experiences that shape adjunct faculty perceptions on disciplinary literacy, writing-in-the-disciplines, and professional writing. Findings from this study include implications for practice and further research. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]