Modeling is a key task in order to analyze, understand, and improve business processes and organizational structures, and to support the design, implementation, and management of information and communication technologies in general and knowledge management systems (KMSs) in particular. Process-oriented knowledge management (Maier, 2004; Maier & Remus, 2003) is a promising approach to provide the missing link between knowledge management (KM) and business strategy, and to bridge the gap between the human-oriented and technology-oriented views (e.g., Hansen, Nohria, & Tierney, 1999; Zack, 1999). However, existing modeling approaches for business processes, including their extensions for KM, still lack concepts to support knowledge work, which is often unstructured, creative, and learning and communication intensive. Recently, the activity theory has been proposed to provide concepts to analyze knowledge work (e.g., Blackler, 1995), but it has not yet been integrated with business process modeling for designing KM initiatives and KMSs. The following sections analyze the characteristics of knowledge work, distinguish important perspectives for modeling in KM, and discuss extensions of process modeling approaches including activity modeling. Then, the process-oriented and the activity-oriented perspectives on knowledge work are compared and connected by means of the concept of knowledge stance.