The United States National Preparedness System has evolved significantly in the recent past. These changes have affected the system structures and goals for disaster response. At the same time, actors such as private businesses have become increasingly involved in disaster efforts. In this paper, we begin to fill the gap in the cross-sector literature regarding interactions that have systemic impacts by investigating how the simultaneous processes of systemic change and intensifying cross-sector interaction worked and interacted in the context of the preparedness system. We examine these inter-linkages through a qualitative study in the setting of Hurricane Sandy. Drawing from systems theory, we develop a grounded model that provides an explanation for the system change and highlights how cross-sector interaction relates to the changes observed in the system.