CSCL scripts facilitate cooperative learning by constraining the activities of co-learners and thereby supporting coordination between distributed co-learners as well as guiding co-learners through the collaborative learning process. So far, such scripts have been encoded in CSCL environments and their tools. This made flexible adaptations of scripts an expensive task, which hinders experience-based improvements of CSCL scripts. In this chapter, we present a formal model of CSCL scripts and show how it can be used to help teachers and designers develop, adapt and experiment with CSCL scripts. In our approach, a script is represented as an extended finite state automaton, which is used to control the user interface and the possible activities in a web-based CSCL environment. We distinguish between atomic scripts, which support a specific collaborative learning activity, and composite scripts, which support a complex collaborative learning task through a sequence of atomic or composite scripts. Scripts can be created by a two-step process: defining atomic CSCL scripts, and linking existing scripts into a composite script for the overall learning activity. This approach enables the definition and reuse of CSCL scripts as well as their adaptation to learning groups and learning situations.