This paper reports the preliminary results of a humanrobot dialogue analysis in the real world with the goal of understanding users' interaction patterns. We analyzed the dialogue log data of Roboceptionist, a robotic receptionist located in a high-traffic area in an academic building [2][3]. The results show that (i) the occupation and background (persona) of the robot help people establish common ground with the robot, and (ii) there is great variability in the extent that users follow social norms of human-human dialogues in human-robot dialogues. Based on these results, we describe implications for designing the dialogue of a social robot. Keywords Human-Robot dialogue, speech-based interaction, Human-Robot Interaction ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous. Copyright is held by the author/owner(s). CHI 2009, April 4 ? 9, 2009, Boston, MA, USA ACM 978-1-60558-247-4/09/04. Min Kyung Lee HCI Institute Carnegie Mellon...