Much of the research in the area of Knowledge Management (KM) has been at the individual level. However, KM literature argues for knowledge processing capacity at an organisational level to enhance organisational performance. This paper argues that there are additional levels of knowledge processing that need to be studied such as teams and communities of practice. The paper presents a theoretical model for investigating the impact of knowledge systems on different levels of and inter-level knowledge processing. Knowledge portals are used as an example of a KM system that facilitates knowledge flows. A framework for classification of portals is presented. Drawing from three theoretical foundations, a theoretical model explaining the impact of knowledge portals on levels of KM is presented. The model focuses on the impact of the knowledge portals on learning, agility and decision-making. Implications and directions for future research, including research propositions, are presented.