Endothelial cells express two classic cadherins, VE-cadherin and N-cadherin. The importance of VE-cadherin in vascular development is well known; however, the function of N-cadherin in endothelial cells remains poorly understood. Contrary to previous studies, we found that N-cadherin localizes to endothelial cell–cell junctions in addition to its well-known diffusive membrane expression. To investigate the role of N-cadherin in vascular development, N-cadherin was specifically deleted from endothelial cells in mice. Loss of N-cadherin in endothelial cells results in embryonic lethality at mid-gestation due to severe vascular defects. Intriguingly, loss of N-cadherin caused a significant decrease in VE-cadherin and its cytoplasmic binding partner, p120ctn. The down-regulation of both VE-cadherin and p120ctn was confirmed in cultured endothelial cells using small interfering RNA to knockdown N-cadherin. We also show that N-cadherin is important for endothelial cell proliferation and motility. These findings provide a novel paradigm by which N-cadherin regulates angiogenesis, in part, by controlling VE-cadherin expression at the cell membrane.