CubeSat Propulsion Busek Co. Inc. has developed several types of thruster systems for CubeSat missions and other small spacecraft. These include the electrospray thrusters, micro-resistojet, pulsed plasma thrusters, RF ion thruster and a green monopropellant thruster. For over 25 years, Busek Co. Inc. has been working to develop electric propulsion (EP) for spacecraft culminating in flight demonstration missions on small satellites. The appeal of EP is that it offers exceptional propellant efficiency (compared to traditional chemical propulsion), which in turn gives spacecraft the capability of performing large delta-V maneuvers at the cost of relatively little propellant. Though developed for small satellites, Busek is actively miniaturizing its EP systems to mass, volume and power consumption relevant to CubeSat and small spacecraft applications. This work has resulted in the development of four EP technologies, each of which allows CubeSats to achieve a performance niche previously attainable only in their larger counterparts. Applications range from precision attitude control (10uN-s impulse bits) to large delta-V maneuvers (up to 410m/s in less than 1U volume). Each of the four EP systems - electrospray thruster, microresistojet, micro pulsed plasma thruster and RF ion thruster - are near or under 1U volume and include propellant storage and management, as well as power electronics and digital interface to the host spacecraft. Also included in this class of thrusters is the green monopropellant thruster in a 1.5U package.