Scripts for computer-supported collaborative learning (CSCL) offer socio-cognitive scaffolding for learners to engage in collaborative activities that are considered beneficial for learning. Yet, CSCL scripts are often criticized for hampering naturally emerging collaboration. Research on the effectiveness of CSCL scripts has shown divergent results. This article reports a meta-analysis about the effects of CSCL scripts on domain-specific knowledge and collaboration skills. Results indicate that CSCL scripts as a kind of socio-cognitive scaffolding can enhance learning outcomes substantially. Learning with CSCL scripts leads to a small positive effect on domain-specific knowledge (d = 0.20) and a large positive effect on collaboration skills (d = 0.95) compared to unstructured CSCL. Further analyses reveal that CSCL scripts are particularly effective for domain-specific learning when they prompt transactive activities (i.e., activities in which a learner's reasoning builds on the contribution of a learning partner) and when they are combined with additional content-specific scaffolding (worked examples, concept maps, etc.). Future research on CSCL scripts should include measures of learners' internal scripts (i.e., prior collaboration skills) and the transactivity of the actual learning process.Keywords Collaboration scripts . Collaboration skills . Computer-supported collaborative learning . Domain-specific knowledge . Socio-cognitive scaffolding . TransactivityResearch on computer-supported collaborative learning (CSCL) deals with the question how digital technologies can be used to help groups of learners collaborate on a high level Educ Psychol Rev (2017) University of Augsburg, Universitätsstr. 10, 86159 Augsburg, Germany (Koschmann 1996). A high level of collaboration is reached when groups of learners engage in certain socio-cognitive activities such as explaining (Webb et al. 2009), questioning (King 1998), or arguing (Andriessen, Baker, andSuthers 2003). Through an engagement in such activities, students are assumed to acquire both domain-specific knowledge (i.e., knowledge about the topic that is discussed within the group) and cross-domain skills such as collaboration skills or argumentation skills. In short, collaborative learning is credited for its high potential to facilitate learners' cognitive development (Mugny and Doise 1978;Schwarz and Linchevski 2007). However, as prior research on collaborative learning-both in face-to-face and in computer-mediated settings-has shown, learners often have difficulties engaging spontaneously in beneficial collaborative learning activities (Cohen 1994;Kuhn, Shaw, and Felton 1997). In this article, the term Bunstructured collaboration^is used to refer to such situations in which learners are not supported with respect to their collaborative learning activities.To overcome these problems, learners can be supported by means of socio-cognitive scaffolding that guides them through collaborative activities that enhance learning. In computer-supported lea...