This study examines opening and closing segments in instant messaging (IM) and demonstrates how openings and closings differ between oral conversation and instant messaging as well as the factors that account for the difference. Many researchers have discussed the differences and similarities between spoken and written languages. Tannen (1980) claims that spoken and written languages are not distinct categories and there is a continuum between them. She also holds that interpersonal involvement is one of the factors that determine if a particular communication is closer to spoken communication or written communication. I will analyze IM, which is best thought of as a communication mode that resides in the middle of the continuum between spoken and written language. Beißwenger (2008) studied the turn-taking of IM and argued that contributions to instant message dialogues are achieved as individual tasks rather than through interactions between participants. He holds that the nature of the individual tasks provides the most important characteristic which distinguishes IM from oral conversation. Closings in IM were studied by Raclaw (2008), who found two patterns of closing: one is an expanded archetype closing which is similar to oral conversation, and the other is a partially automated closing which is totally different from oral conversation because an automated message terminates the conversation. He did not discuss the characteristics underlying the two patterns of closing in instant messaging. I reanalyzed the argument by Raclaw utilizing a segment of instant messaging from my data, and discovered that what characterize the two patterns of closing in instant messaging are the nature of interpersonal involvement and the nature of the individual tasks. These reflect the characteristics of spoken and written communication respectively. In this study it was found that characteristics of IM communication fluctuate between spoken and written communication. Instant messaging resides in the middle of the spoken and written continuum, but whether it exhibits characteristics of spoken or written communications can vary depending on the way participants contribute to the conversation.