We focus on the molecular and cellular events that shape the early vertebrate embryo, particularly the formation of the embryonic body, using zebrafish as a model system. The vertebrate body grows from the neck down by the progressive addition of cells from a mesodermal progenitor population located at the most posterior end of the embryo. A major interest in the lab is to understand the mechanisms that regulate this process. Our focus is on the signaling factors that pattern and sustain the mesodermal progenitors, including Wnts, Fgfs and Bmps, and their interaction with transcription factors that regulate the progenitors, particularly members of the T-box family. Recently we have become interested in how proliferation of the progenitors is integrated with differentiation, since the embryo needs to carefully coordinate these processes.