Prof Robert Weinberg explains what he presented at NCRI 2010 regarding the mechanisms of cancer cells disseminate within the body and the formation of metastases in distant tissues. Although this process appears to be complex, activation of just one normally latent embryonic programme known as epithelial-mesenchymal transition (EMT), is sufficient for cancer cells to disseminate. Prof Weinberg speaks about the stages necessary for cancer cells to change from primary tumour cells to a form that can migrate to distant sites and discusses the role of mesenchymal cells and the signalling between mesenchymal and carcinoma cells. Prof Weinberg explains how the EMT can convert epithelial carcinoma cells into cancer stem cells with the ability to initiate new tumours and outlines his hope that we will eventually be able to reverse this process. Prof Weinberg concludes by discussing the session he will be chairing on the recruitment of stromal cells by carcinomas.