The members of the Dynamic Robotics Laboratory explore, design, and build robotic systems that move swiftly and can easily handle impacts and kinetic energy transfer. Examples include walking and running robots, force-controlled actuators for delicate tasks such as bomb defusing, lower- and upper-extremity powered prosthetic limbs, exoskeletons for military use or assisted mobility for disabled persons, or catching a ball in the air. Many of these tasks are difficult or impossible for traditional robots due to fundamental limitations of the hardware, such as motor inertia and torque limits. The dynamics of the mechanical system are an inseparable aspect of the behavior of a robot, and can be either a limitation or an asset; thus, our approach integrates the design of the hardware dynamics with the design of the active software controller. Novel actuator designs and mechanisms combined with complementary software controllers can lead to robots that are as dexterous and agile as humans.