Thin-wings impose a unique combination of demanding requirements on a primary control-surface servoactuator. To address these requirements, a rotary servohinge actuator has been developed by HR Textron Inc. (HR). It uses a large lead-angle, recirculating ballscrew to convert linear motion of a conventional hydraulic actuator to rotary motion. This paper describes the thin-wing problem in detail, explains the rationale for selecting the adopted design, and discusses the actuator design and development program. A summary of servohinge performance and progress of the test program also is provided. The servohinge and electronic controller were delivered to the McDonnell Aircraft Company in support of the WRDC (USAF)-sponsored Advanced Development Program (ADP).