A mathematical model predicting height growth for released grand fir regeneration is presented. Data used to develop the model indicate that response to release depends on tree characteristics and site conditions interacting with physiological shock. Release is better on cool, moist sites but depends highly on the vigor of the tree before release. Tall trees which are equally or more suppressed by the overstory do not respond as well as short trees. Logging damage decreases response. Recommendations for releasing stands of advance grand fir and guidelines for thinning released stands are provided. Forest Sci. 26:537-545.