Abstract: A multiple stage rotary compressor having a housing with a pump cavity and an orbiting ring piston in the cavity. A cylindrical post carried by the housing within the orbiting ring. A pair of vanes engaging the outer surface of the orbiting ring to define first-stage having a pair of primary pumping chambers in the cavity. A second pair of internal vanes contacting the inner surface of the orbiting ring to define a second-stage having a pair of secondary pumping chambers. A capacity control mechanism applied to the first-stage operative to limit the compressor capacity to the second-stage only. A second capacity control mechanism applied to the second-stage operative to variably bypass second-stage discharge to second-stage suction. The plurality of capacity controllers operating to establish varying compressor pump capacity depending upon the operating requirements of the compressor.