We use Goffman?s characterization of "front" and "backstage" interaction practices to analyze how the use of instant messaging in both face-to-face and technology-mediated meetings alters interaction boundaries. In an interview study of workers in two organizations, we found that workers used instant messaging during both face-to-face and technology-mediated meetings (1) to participate concurrently in "front" and "backstage" interactions, (2) to participate in multiple, concurrent, "backstage" conversations, and (3) to manage and influence front stage activities through concurrent backstage conversations. These interactions would be either physically impossible or socially constrained without the use of instant messaging. We draw on psychology, GSS, and communication studies to consider the implications for group effectiveness.