This chapter explores the act of professional writing. The analysis shows that a professional writer needs to master the linguistic code but also high level written communication skills (Beaudet, 2010; Clerc & Beaudet, 2008; Labasse 2008). By analogy to the research about the two processes reading, analytical reading and global reading, we hypothesize that the expertise of a " professional writing " is on the co-management of the analytical writing and the global writing. The writing process must be done within an overall writing effort integrating elements of denotation and connotation of the co-enun-ciators. For that, we will compare the practice of professional writing to his " interactional effectiveness " (Clerc & Beaudet, 2008; Romain, Pereira & Rey, 2015). Our corpus consists of editorials, claim forms, and other written communication published by a general council and by a French city, and written materials for a site on urban den-sification. The goal of this analysis is to identify the elements of the functional writing and those of professional writing by studying the language skills: technical writing, discourse analysis , interactional pragmatic, linguistic politeness, and rhetoric. We will observe the organization of the technical elements of writing; language choices (methods of inquiry and skill, speech acts,. . .) leading to the development of an interperson-al relationship and specific interdiscursive elements; tools of linguistic politeness in the service of clarity and informative-ness; and tools of rhetoric in the service of persuasion and the fit between form and content.