More and more educators and researchers use ict-tools to support collaborative learning. Research has shown that, for collaborative learning to be more effective than individual learning, individual learners have to achieve a sufficiently common cognitive frame of reference, or common ground. This common ground does not appear by itself, but rather often needs to be negotiated. This negotiation is seen as an important aspect of collaborative learning. This article presents a study with ntool, an ict-tool to support the negotiation of common ground. Ntool supports learners in making their individual perspectives explicit to others so that common ground can be negotiated. Two versions of the tool differing in the extent to which users were coerced into adhering to embedded support principles were used in a secondary vocational education setting. Coercion, as expected, increased negotiation of common ground in both settings. However, results were contradictory with regard to the extent to which common ground was achieved. Overall, it can be concluded that ntool and its underlying framework affect negotiation of common ground, and that adding some coercion increases this effect. However, when learners have no prior experience in collaborative complex problem-solving, ntool may only affect surface aspects of communication.