Habitat conservation plans (HCP’s) often are necessarily developed despite considerable uncertainty regarding how species are likely to respond to future conditions.  Adaptive management – a process of model-based decision making that involves iterative prediction, measurement, and model-updating – offers an approach to managing under uncertainty and is now a required component of HCP’s.  The adaptive management components of the Etowah Aquatic HCP, developed for imperiled stream fishes in an urbanizing basin of the southeast US, are (1) models that predict species persistence and abundance given HCP implementation, (2) a monitoring program designed to test those predictions and provide data for improving the models, and (3) a process for using updated models to guide future development decisions.  The jurisdictions participating in the HCP understand the necessity of monitoring fish populations and stream habitat to test model predictions, and that future data may show that the species covered by the HCP are more or less sensitive to development than current conditions indicate.  Thus, the HCP allows for adjustment in policies that regulate development if necessary either to improve species protection or, if species prove less sensitive than predicted, to lessen regulatory requirements to the level actually needed.