The nature of computer-supported work varies widely, from settings in which the employee's total task is completed through the use of information technology, to settings in which the employee must determine how and when to use one or more technological tools in task performance. In the latter situation, the employee may be a knowledge worker already confronted with a difficult, non-routine task that requires significant cognitive effort and in which the knowledge worker is expected to apply his or her own knowledge capital (Davis et al., 1993). What impacts are expected from high complexity work settings like the use of information technology (IT) in knowledge work? The research on work redesign has focused on increased task complexity as beneficial, and has foundthat changes in the work setting that increase workers' perceptions of task complexity are related to increased motivation, satisfaction, and in some cases, performance (Griffin, 1991). Other researchers have found negative impacts of high complexity work(Banker et al., 1993; Schroder et al., 1967). However, research also shows that some of the negative impacts of high complexity work can be mitigated by increasing the level of cognitive information of an individual (Campbell & Gingrich, 1986; Khalil & Clark, 1989). These seemingly conflicting results suggest that the relationship between high complexity work and task outcomes is neither simple nor deterministic, and that the interplay between individual differences and the work setting are key to understanding the relationship. When MIS provides IT support for high-complexity knowledge work tasks, it may need to consider the characteristics of that IT, how that IT may interact with the knowledge worker's tasks, as well as the users' capabilities in order to predict outcomes like performance and satisfaction. The purpose of this paper is to (1) integrate the existing literature on complexity and (2) describe an interactionist model of complexity which attempts to include the various elements of complexity. The interactionist model of complexity is a framework that can be used to enhance our understanding of complexity in the context of computer-supported knowledge work, and support research on the relationship of complexity to important organizational outcomes.