Microblogging has recently generated a lot of research interest. Yet very little is known about how corporate employees use microblogging tools. This study examined microblogging in the workplace by conducting a content analysis comparing posts from individuals who were using an internal proprietary tool and Twitter simultaneously. In both settings, posts that provided information or were directed to others were more common than posts on status. Within these categories, it was more frequent to provide information externally than internally but more common to ask questions either through broadcast or directed posts internally than externally. Qualitative interviews explored users' motivations regarding microblogging behavior. The paper concludes with a discussion of the implications of microblogging for business use. Copyright © 2010, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved.