This article examines how Instant Messaging (IM) systems help employees of a Korean organization improve their relationships with their coworkers within and across organizational boundaries—within departments, between departments, and outside the organization. We briefly review literature about IM in developing working relationships and build our research questions. We then provide data analysis results based on a survey and structured interviews. Subsequently, in an exploratory case study of two individuals, we extend the analysis of departmental boundaries by including hierarchical levels, job profiles, and different communication purposes. Quantitative Social Network Analysis and visualization are used to analyze the communication pattern of the two individuals.