During plant embryogenesis, the future body plan of the plant is laid down. Part of this development is the specification of cell identities: the outer epidermis, the middle ground tissue and the inner vascular cells. In this thesis we have looked at the genetic components that control plant vascular identity. We have traced back the first vascular cells to the 16-cell embryo and discovered that the development of vascular identity is not a single step but rather a multi-step process. Upstream of this multi-step process we discovered a large set of candidate regulators that control vascular identity. After focusing one of these candidates we now hypothesize that the protein GBF2 can regulate vascular gene expression. Together with proteins that act downstream of the plant hormone auxin, GBF2 interacts with specific DNA sequences to regulate the initiation of vascular development.