Abstract : Free collaboration does not systematically produce learning. One way to enhance the effectiveness of collaborative learning is to structure interactions by engaging students in well-defined scripts. A collaboration script is a set of instructions prescribing how students should form groups, how they should interact and collaborate and how they should solve the problem. In computer-supported collaborative learning (CSCL), the script is reified in the interface of the learning environment. This contribution dismantles the concept of script. Syntactically, a script is sequence of phases and each phase can be described by five attributes. The grammatical combination of these elements may however produce any kind of pedagogical method, even those that have nothing to do with the idea of collaborative learning. On the one hand, the definition of scripts constitutes a promising convergence between educational engineering and socio-cultural approaches but, on the other hand, it drifts away from the genuine notion of collaborative learning. Will the fun and the richness of group interactions survive to this quest for effectiveness? The answer depends on the semantics of collaborative scripts: what is the design rationale, what is the core mechanism in the script through which the script designer expects to foster productive interactions and learning?