In spite of the best efforts of researchers and practitioners, Information Systems (IS) developers are having problems "getting it right". IS developments are challenged by the emergence of unanticipated IS characteristics undermining managers ability to predict and manage IS change. Because IS are complex, development formulas, best practices or development guides simply will not work. The difficulties in these system developments stem from the "complexity" of IS arising from the inter-relationship, interaction, and interconnectivity of the elements in the system and its environment. This research uses complexity concepts to help solve the problem with IS development and explain why so many IS developments fail. It uses Complexity Theory to understand and explain IS development as an emergent phenomenon where the system is "attracted" to certain configurations. This research derives and validates a detailed IS change "model and method" enabling IS developers to understand the unpredictable and unanticipated outcomes of information systems and avoid failures. The model uses Complex Adaptive Systems concepts, the Chaos Theory "strange attractor," and state space analysis to identify when IS states are susceptible to failure rather than trying to identify the myriad causes that may or may not contribute to failure. The method uses structured case study analysis and grounded theory techniques fitting a general model to specific IS producing the best possible model for the system. This research extends previous work in the application of Complexity Theory to IS and is the first to apply these theories to Public Safety Network information systems. In practice this research can help managers understand the impact and temporal validity of their decisions on IS development and their organization. Findings generalize to a broad range of cross-agency intergovernmental collaborations employing IS. This research should spur further studies utilizing Complexity Theory for both public and private sector IS and lead to improvements and better understanding of the development and evolution of Public Safety Networks, an increasingly common and important component of homeland security and emergency management. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]