Interprofessional shared decision making (SDM), where medical oncologists, general practitioners, and nurses collaborate, is essential for allowing healthcare professionals (HCPs) and incurable cancer patients to choose treatment best fitting a patient’s end-of-life wishes. The aim of this dissertation was to effectively promote interprofessional SDM in palliative cancer care through communication skills training (CST) for HCPs. First, in two qualitative interview studies, the role of 1) GPs and 2) hospital nurses in SDM in palliative (cancer) care was explored. We found three strategies HCPs may deploy to support SDM: 1) checking the quality of a decision, 2) complementing SDM, and 3) enabling SDM. Second, the effects of CST in SDM were examined. A review of reviews on the current evidence for CST revealed that CST can probably improve HCPs’ communication skills, but that high-quality research is needed to increase the certainty of evidence on CST effects. Two one-group pre-posttest studies demonstrated 1) a large effect of a blended CST, i.e. e-learning and online training session, in SDM on medical oncologists’ skills and 2) a medium effect of a blended CST in SDM support on GPs’ and hospital nurses’ skills. An experimental study showed that, in contrast to these observations of professional assessors, cancer patients and survivors did not significantly differ in their assessments of trained and untrained HCPs in SDM support. In conclusion, CST seems helpful in promoting interprofessional SDM in palliative cancer care. Yet, research designs should be improved and the clinical relevance of CST established.