This chapter examines professional illustration expertise through the lens of Charles (Goodwin in American Anthropologist 96:606–633, 1994) concept of professional vision, which highlights the socially organised discursive practices used by professionals to construct and sustain specialised knowledge. Using a thematic analysis of contemporary illustration resources, the chapter examines how expertise is constructed and communicated through these materials. The study identifies three overarching themes of expertise: illustrative skills, communication processes, and professional practice, each represented through distinctive terminology within the resources. It highlights how technical expertise, such as drawing skills and media application, is emphasised through literal terms, while non-technical expertise, like cognitive resources and conceptual drawing, is often conveyed metaphorically using terms like “voice”, “vision,” and “visual language”. The findings suggest that the strategic use of discursive practices in illustration resources not only frames the profession’s knowledge but also influences how practitioners, students, and educators understand and apply expertise in diverse contexts. This chapter contributes to broader discussions on the discursive construction of professional knowledge and offers insights into the interplay between technical and conceptual dimensions of illustration expertise.