Through language, humans have the capacity to instruct others to perform parts of a collaborative task. Receiving verbal instructions on upcoming tasks has been shown to activate a corresponding task set, which in turn can affect the execution of presently ongoing task behavior (“instruction-based reflexivity”, Liefhooge et al., 2012). Here we investigate whether such preparatory task sets are also formed when giving verbal instructions to a task partner. In a series of four experiments, we adapted the instruction-based reflexivity (IBR) paradigm to investigate whether instructing another person leads to processing the instruction content and thus forming a corresponding task set on behalf of the task partner (Experiment 1). In addition, we tested if the formation of such shared task sets is induced by the collaborative task (i.e., the act of instructing the task partner), or rather by the instructor merely reading (i.e. Experiment 2, 3), hearing (i.e. Experiment 3), or repeating the instructions aloud (i.e. Experiment 2, 3), without having a task partner. In Experiment 4, we directly compared collaborative and individual contexts, to determine whether the shared task sets could alternatively be explained by lower-level characteristics of the task. We found evidence for the formation of task sets in response to instructing a task partner. These effects however are rather small and seem to be, at least in part, elicited by lower-level characteristics associated with the act of verbalizing instructions.