This article examines issues in conducting economic impact analyses in regions undergoing substantial or rapid transformations. Economic impact analysis methods, like many other analytical techniques, are predicated on economic stability, yet commonly are applied to situations that violate this condition with little consideration of the implications. Special attention is paid to regional input–output modeling because of its prevalence in economic impact studies and susceptibility to distortions. Advice and suggestions for practitioners and educators teaching analytical techniques are discussed. Military communities in the United States impacted by the 2005 round of base realignments provide illustrative examples and applications.