This volume contains the scheduled technical proceedings of the Estes Park Advanced Propulsion Workshop, 19-22 September 2016, Estes Park, Colorado. The workshop was modeled on the famous Shelter Island conference, and it drew together theorists and experimentalists working in the field of breakthrough propulsion. The sessions were structured to allow two hours per concept, with detailed audience interchange. The Space Studies Institute has made available videos of the workshop. This volume collects prep material sent to participants before the meeting, proceedings papers for each session, and a summary of the session discussion. Two propellantless propulsion devices received special consideration. One was based on a clever electromechanical manipulation purported to couple into the gravitational field of the universe, called by its inventor the Mach effect. Another purported to produce thrust with a simple, asymmetrically-shaped microwave cavity, sometimes called an EM-drive, for electromagnetic drive.