Research shows that action observation can prime execution. Evidence for this comes from experiments that show that action observation influenced temporal (e.g., speed) or spatial (e.g., peak grasp aperture or trajectory) aspects of executed movement. In the paper presented here, we for the first time show that observation can also prime executed action force. Following observation of force actions, participants executed grip-force responses using a dynamometer, and the data showed that their force was modulated by the condition observed. The findings of the study are discussed in terms of a likely cause of the force modulation effect and potential uses that the effect may have for strength rehabilitation.