This research deals with the mechanical interaction of parts with each other and with a robot during an assembly operation. Since friction is an important element of these interactions, techniques will be developed to exploit friction, enhancing both the capabilities and the reliability (robustness) of robotic assembly operations. One technique involves force-controlled manipulation in which the relationship between the force sensed by the robot arm and the displacement of the arm from a nominal position can be specified. A theoretical understanding of assembly operations performed by a force-controlled robot will be sought, with the objective of finding and implementing algorithms for the automated planning of such assembly operations. The important, but more difficult, inverse problem of designing parts which are easy to assemble will be considered.