ESL (Execution Support Language) is a language for encoding execution knowledge in embedded autonomous agents. It is similar in spirit to RAPs and RPL and RS and its design owes much to these systems. Unlike its predecessors, ESL aims for a more utilitarian point in the design space. ESL was designed primarily to be a powerful and easy-to-use tool, not to serve as a representation for automated reasoning or formal analysis (although nothing precludes its use for these purposes). ESL consists of several sets of loosely coupled features that can be composed in arbitrary ways. It is currently implemented as a set of extensions to Common Lisp, and is being used to build the executive component of a control architecture for an autonomous spacecraft.