On 15 June 1973, a shallow-focus earthquake with magnitude mb 4.8 occurred in southern Quebec, in an area that has a record of only a few minor earthquakes during the previous 200 years. This event was felt throughout southern Quebec, eastern Ontario, and the New England States, to a distance of 300 km from the epicenter. A small amount of minor damage to plaster and chimneys occurred in the immediate epicentral area, indicating a maximum intensity of VI. The focal mechanism solution suggests that the earthquake was the result of primarily strike-slip movement along a plane trending northeast or a plane trending northwest. Arguments are presented that this event is part of the seismicity associated with the northern Appalachian Mountains.