Instant Messaging (IM) is becoming a mainstay for online one-to-one communication. Although IM is popularly described as a written version of informal speech, little empirical investigation of the linguistic nature of IM exists. Moreover, although gender issues are being addressed for one-to-many forms of computer-mediated communication, we have no comparable studies of IM. This article offers a linguistic profile of American college student IM conversations. In addition to analyzing conversational scaffolding and lexical issues, the article identifies gender divergences in IM usage. Some differences reflect commonly reported functional gender distinctions in face-to-face spoken conversation; other differences indicate gender-based attitudes toward the importance of language standards in speech and writing.