For the last two decades systems developers and researchers have largely assumed that the process of developing business information systems is a wellstructured, project-oriented, once in a lifetime undertaking. However, present business models that are intensively reliant on information technology are rendering this perception obsolete. There has been a growing propensity toward increasingly iterative, fastpaced, user-driven systems development methodologies such as Rapid Application Development, Unified Modeling Language, Joint Application Development and the Relationship Management methodology (Hans- Werner1997; Isakowitz, 1995; Shapiro, 1997; Vessey, 1994). At the same time the discipline of information systems has witnessed an increasing awareness of the importance of systems maintenance - with the general proposition that systems development is an everproceeding activity (rather than a project-based activity) - becoming the norm (Howard 1990). The majority of empirical research on systems development, to date, has tested the contributions of different types of knowledge to effective systems development. Much research has also been done on how different methodologies for systems development impact the quality, effectiveness, and efficiency of resultant business information infrastructure. The studies suffer from one or more of the following limitations: (1) They largely perceive information systems evolution via systems development as generally being a slow, linear, structured and continuous process. Current events in the information systems and electronic commerce sectors indicate that systems development is highly dynamic, discontinuous and adaptive in nature – the defining traits of a complex system. (2) Though most of the past studies recognize that systems development is a knowledge intensive activity, rarely is it seen as a primary mechanism by which a firm embeds knowledge into its business information infrastructure’s technologies, databases and automated operating procedures. Because almost all business functions and transactions within an electronic commerce enterprise is achieved via the firm’s business information infrastructure, enhancement of business knowledge and information within such a firm is expected to be heavily dependent on the enhancements made to that infrastructure via specific systems development approaches. In rapidly evolving environments as characterized by present day electronic commerce, methodologies become a primary means by which the firm continuously updates its knowledge resources hence sustaining or leveraging its competitive advantages. The theory of complexity may contribute to the perception and re-classification of systems development methodologies in such a manner as to provide a clearer understanding of which methodologies are best suited for directing the development and enhancement of business information systems in today's electronic commerce economy. By viewing business information systems as emergent complex adaptive systems, the methodologies employed to derive these systems can be seen as being synonymous to the natural rules that govern the behavior of all natural phenomenon. Thus it enables us to explain what methodologies best match a specific systems development or enhancement tasks allowing for the development of better quality business information systems, especially for electronic commerce applications.