ABSTRACTData that constrain theoretical pictures of how the universe was reinonized during the roughly first billion years after the Big Bang are sparse. This is the era when the building blocks of our cosmos formed, i.e., the first stars and galaxies. As a result, there is a troubling gap in the cosmological record. The Murchison Wide-field Array (MWA) is an 8000-element radio interferometer being built in Western Australia, intended to make first detections of the evolving angular power spectrum of neutral Hydrogen in the intergalactic medium during reionization. The project is shaking down a 5% demonstrator and testbed prior to build out. I will discuss basic design principles, including the novel use of High Performance Computing based on GPUs, report on the status of the project, and describe a proposed progression of pathfinders leading to a low-frequency square kilometer array somewhat after 2020.