Many of the affordances associated with computer-based learning environments are due to their interactive nature. Such interactive learning environments do not merely present information like a book or an instructional video; instead, they permit learners to actively engage in order to learn. Although at first glance it would seem clear what the terms “interaction” and “interactive” mean in the context of learning environments, there is, in reality, little agreement regarding these terms in the corresponding literature. There are almost as many different definitions as articles that attempt to illustrate these terms (see, e.g., Betrancourt 2005; Kennedy 2004; Kettanurak et al. 2001; Mayer 2001; McMillan 2002; Rafaeli 1988; Wagner 1994). Whereas some characterizations of interaction detail how such an interchange between learners and a learning environment might occur (e.g., control over pace, having influence on what will be presented and how this is done), we propose a rather general definition for the purpose of this Special Issue. Similar to Wagner (1994), we define interactions in the context of computer-based learning as a process in which the “actions” executed by learners and their learning environment are mutually dependent on each other. The mutual dependence of actions can be due to technical features of learning environments (e.g. problem-solving interfaces) or to the fact that cooperation with others is afforded by the technology. Examples of interactivity that were considered in this Special Issue are dialoguing, controlling, manipulating, searching, and navigating in learning environments with multiple presentation modes (Moreno and Mayer 2007); sequencing, controlling contents, and representation format in hypermedia environments (Scheiter and Gerjets 2007); pacing (i.e., control over the continuation) of a video-based model; controlling over appearance and task selection with respect to the model (Wouters, Tabbers and Paas 2007); predicting, reacting to reflection, or self-explanation prompts in example-based environments (Atkinson and Renkl 2007; Wouters et al. 2007); problem solving with intelligent Educ Psychol Rev (2007) 19:235–238 DOI 10.1007/s10648-007-9052-5