Since 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) has detected nearly 100 gravitational waves from merging black holes across the Universe. But despite this wealth of new astronomical data and the enormous questions it can answer (How fast is the universe expanding? What is dark matter? How are stars and galaxies made over cosmic time?), we still do not know how where any of these black hole binaries are coming from! I am proposing the Binary Black Hole Origins Project to combine our best theories of binary formation into a single, physically self-consistent framework. Using state-of-the-art models of evolving stars and star clusters, we will finally be able to untangle the origin of LIGO’s gravitational waves, paving the way for the next 30 years of astronomy with black holes.