National infrastructure systems are increasingly being challenged to deliver what societies require of them. This includes the need to address the de-commissioning of ageing infrastructure assets, rapid demographic change and a variety of environmental pressures, while critically maintaining economic competitiveness. It is thus crucial to understand more about the economic forces that influence both the supply and demand for infrastructure, and the nature of the economic interdependencies that exist between different components and sectors of the infrastructure stock. However, much of our understanding of infrastructure economics is based on models that adopt assumptions that seem to be rather at odds with the reality. This article argues that we need to reframe our thinking of infrastructure systems and this can be achieved by utilising concepts drawn from complex adaptive systems (CAS) theory. It can help recognise the interdependencies that exist between supply and demand, between infrastructure sectors, and how the agents of national infrastructure systems tend to adapt and co-evolve over time. This perspective is illustrated with a case-study example of Information Communications Technologies (ICT) infrastructure, where this complex adaptive lens is found to be particularly amenable for thinking about this sector. Further research should use this lens to examine the workings of other infrastructure sectors, as well as move away from theory to critically review the quantitative methodologies utilised in the field. This should include their potential applicability to understanding infrastructure systems, with the ultimate goal of improving decision making and the formulation of national infrastructure strategies.