This article reports on the design of a three-arm, nonrandomised controlled trial of interventions targeting social communication skills following traumatic brain injury (TBI) in adult participants. People with severe TBI were allocated to one of the three groups: the TBI group, where only the person with TBI was trained, the JOINT group where both the everyday communication partner (ECP) and the person with TBI were trained together, and a delayed treatment control condition. The trial is comparing whether including everyday communication partners in the training process provide additional benefit when compared to training the person with TBI alone; and additionally, whether training the person with TBI alone is more effective than no training. A range of primary and secondary outcome measures will be used to evaluate outcomes. Publishing the protocol prior to the results of the trial being available has several important benefits (Godlee, 2001). The original hypotheses and intentions of the research are made explicit to ensure that the process of conducting this clinical trial is transparent to readers, and so that comments may be made before results are finalised. It provides the opportunity to outline a detailed description of this intervention and methodology, or to acknowledge changes to methodology, which may assist with eventual clinical application of the intervention. This article also informs the research community of the work that is underway to promote opportunities for collaboration and reduce unnecessary duplication of research. The protocol for this trial has previously been registered on Current Controlled Trials (http://www.controlled-trials.com/ISRCTN57815281).