This paper describes a minimalist mobile robot design approach that offers a high locomotive efficiency, and is therefore well suited to mesoscale robot design. The authors have incorporated this approach into the development of a dynamically controlled piezoelectrically actuated mesoscale robot quadruped. The design described utilizes a lightly damped skeletal structure that generates locomotion when vibrationally excited at a skeletal resonance by two piezoelectric unimorph actuators. The skeletal structure consists of four articulated legs used to produce a trot type gait. Each articulated leg moves in two degrees of freedom to create elliptical foot motions that enhance locomotion efficiency and rough surface capability. Directional control is achieved by tuning each leg to a slightly different resonant frequency, so that differential control of leg amplitude can be achieved by modulation of the actuator excitation frequency. Compact power electronics have been developed and self-powered (i.e., battery-powered) operation has been demonstrated. This paper describes the design of the robot quadruped, which has a footprint that measures 9 cm × 6.5 cm and weighs 51 grams without the electronics and 104 grams with them. Data is presented that characterizes the average speed and typical power consumption of the robot at various excitation frequencies.