This paper articulates "critical reverse engineering" with Foucauldian genealogy. It first explores the theoretical bases for reverse engineering, drawing mainly on software engineering literature. The author suggests that reverse engineers do more than simply take apart and document systems; they also trace technical artifacts back to preceding versions, theories of the user, and the organizations that created the artifacts. Next, the article justifies an interest in technologies by connecting reverse engineering with Science and Technology Studies. Finally, it considers the ways in which reverse engineering might inform genealogical inquiry, as well as the limitations of this approach.