This research seeks to unearth Information Technology (IT) use by disaster responders (DRs) deployed by their affiliated disaster response organizations (DROs) for natural disaster response missions. Our on-ground analysis sheds insights into how several types of IT use behavior are surfacing as the DRs concurrently serve the role of a member of the ephemeral disaster response organization and the affiliated DRO. Informed by the role expansion lens, role stacking and its consequential IT use behavior emerge to explain how behavior towards institutional IT tasks is shaped by the location and activities of the DRs. This research expands the understanding of IT use in situations where users are disentangled from a preexisting institutional boundary through mission deployments. Such an understanding is particularly important since providing IT applications to the employees is a substantial investment committed by an institution. However, users do not necessarily use the institutional IT applications in certain situations. © 2022 International Conference on Information Systems, ICIS 2022: "Digitization for the Next Generation". All Rights Reserved.