This study examined infants' use of object knowledge for scaling the manipulative force of object-directed actions. Infants 9, 12, and 15 months of age were outfitted with motion-analysis sensors on their arms and then presented with stimulus objects to examine individually over a series of familiarization trials. Two stimulus objects were used in the familiarization phase, and were identical in size, shape, and material, but different in color and weight. Following familiarization, two test objects that had been hidden from view were presented. The test objects were identical in appearance to the familiarization objects, but their color-weight correspondence was reversed. Infants' actions on the test objects revealed selective, differential preparation for the specific weights experienced during familiarization. Because the objects were equivalent in their visual affordances for action, the differential preparation and coordination of manipulative force was based on knowledge acquired during the familiarization phase. Infants are capable of utilizing object representations to coordinate manipulative force in object-directed actions. (Contains 3 tables and 1 figure.)