This article presents the first installment of "Professional Writing in the English Classroom." The authors begin by answering the obvious question: What is professional writing? It isn't remedial writing, and it involves much more than writing memos, business letters, and resumes (although it certainly includes those genres). Professional writing has many names--"technical communication, technical writing, business communication," and others. Here, the authors use the term "professional writing" because it provides the most flexible definition of the concept: writing within professional contexts. To explore this concept further, the authors examine a genre familiar to most teachers: the "sub plan." (Contains 2 figures.)