Vasculogenesis is the process by which endothelial progenitor cells self-assemble into multicellular, blood-bearing fluidic networks throughout our bodies. If properly harnessed in vitro, this process could facilitate the rapid vascularization of biomaterials, a significant outstanding challenge in the field of tissue engineering and regenerative medicine. We utilize biomaterials, microfabrication, and cell force measurements to understand how endothelial cells utilize intercellular mechanical communication to intelligently organize across significant spatial distances into complex multicellular structures. The overall objective of this work is to understand the role of ECM physical properties, specifically fibrous microstructure, in 1) regulating the self-assembly of endothelial cells into a mature vascular network and 2) promoting host cell invasion and integration with host vasculature upon implantation.