Many applications require the use of multiple, loosely-coupled adaptive computing boards as part of a larger computing system. Two such application classes are embedded systems in which multiple boards are required to physically interface to different sensors/actuators and applications whose computational demands require multiple boards. In addition to the adaptive computing boards, the computing systems for these application classes typically include general-purpose microprocessors and high-speed networks. The development environment for applications on these large computing systems is not unified; development on these systems is time-consuming and platform-specific. A standard ACS API is proposed to provide a developer with a single API for the control of a distributed system of adaptive computing boards, including the interconnection network.The API provides a C-language binding that allows a developer to write a single host program that controls multiple boards. This API is intended to address a wide range of application requirements including embedded systems and cluster-based adaptive computing systems. It allows for source code porting and scaling from small research platforms to large field-deployable platforms. The API is currently targeted to the SLAAC-1, SLAAC-2, and Wildforce platforms.