One of the fundamental requirements for the success of a robotic task is the ability of the control to handle the physical interaction between robot and environment. The quantity that more effectively describes the state of the physical interaction is the contact force. High values of contact force are generally undesirable since they can damage both the robot and the environment. In this chapter, the problem of controlling the physical interaction, modeled as an energy exchange between a mechanical impedance and a mechanical admittance, is first considered. The stability of the coupled system is guaranteed using the concept of passivity. Suitable impedance control and admittance control strategies are introduced, aimed at reshaping the dynamics of the robot based on the dynamics of the environment, modeled as a passive impedance or admittance. In the presence of geometric constraints imposed by the environment, the task geometry allows defining natural constraints set by the environment and artificial constraints set by the control; the constraints are referred to a suitable task frame. If the geometric constraints are available in analytic form, suitable selection matrices can be defined to separate the task directions where the robot is free to move from the constrained task directions. Hence, hybrid force/motion control schemes are derived, where motion and force are controlled along different task directions. This approach is also extended to manage the interaction with compliant environments. The case of redundant robots is finally presented.