This paper introduces an executable coordination specification language, with which both pre-specified and more flexible and generic agent coordination approaches can be expressed. An iterative process was taken to define this language. First, useful language elements were defined, after which example coordination approaches were specified using this language. The language was extended incrementally with new language elements whenever new concepts were required to enable specification of the example coordination approaches. The approaches were simulated and tested using particular test cases. Finally, an evaluation of the coordination approaches was performed by means of formal verification.