The question of Fire-Cracked Rock (FCR) in Woodland contexts has become an important and controversial topic in Western Great Lakes archaeology. There are no clear and widely accepted criteria for distinguishing FCR when the rocks show no observable characteristics associated with fire (heating and cooling). To help overcome this shortcoming, we analyzed both the thermoluminescence (TL) and the optically stimulated luminescence (OSL) of alkali feldspar grains from a series of six samples of FCR from the Hannaford site in northern Minnesota. A geologic unheated specimen from the same geographic area was used as a control sample. A comparison of the luminescence (TL and OSL) intensities of both natural and natural plus artificial dose signals allowed us to demonstrate that the six selected samples of FCR had been effectively heated at the time of archaeological settlement. The good agreement between the TL and OSL results suggests that the OSL method is a viable alternative to TL for the identification of FCR. The OSL method requires less material, can be applied to a large number of samples, and is more cost-effective.