The Natural Conservation Service Curve Number (NRCS-CN) procedure, which predicts runoff volume from a rainfall volume, is a widely used hydrologic model because of its simplicity and convenience. However, its applicability in forecasting runoff from extreme rainfall events on mountain forest watersheds is controversial. As a result, investigation of the NRCS-CN will be conducted under various conditions and settings. In addition, previous modifications of the method will be discussed and compared against the original method and a new improved method will be developed. Experimental forested watersheds selected for this study are Fernow, West Virginia; Coweeta, North Carolina; and Hubbard Brook, New Hampshire. This research will provide a valuable conclusion on the applicability of CN method for mountain forest watersheds.