INTRODUCTIONIn Xenopus laevis, mesoderm can be induced in animal cap cells by contact with vegetal cells (presumptive endoderm). This juxtaposition of tissues was the first indication that the process of mesoderm induction could be separated from neural induction. This protocol describes how to set up a conjugate using Xenopus animal cap and vegetal tissue. In theory, a single embryo can provide both animal and vegetal cells; however, in practice, this is difficult to achieve.